[PATCH v7 0/4] Add support for long task name

[PATCH v7 0/4] Add support for long task name

[Bhupesh]

Changes since v6:
================
- v6 can be seen here: https://lore.kernel.org/all/20250724123612.206110-1-bhupesh@igalia.com/
- As suggested by Linus, we got rid of 'get_task_comm()' entirely and replaced it with
  'strscpy_pad()' implementation.
- Also changed the current memcpy() use-cases which use 'current->comm' to copy the task name over
  to local copies, to call a wrappper like "get_task_array()".
- Collected 'Reviewed-by' from Kees for [PATCH 1/4].

Changes since v5:
================
- v5 can be seen here: https://lore.kernel.org/lkml/20250716123916.511889-1-bhupesh@igalia.com/ 
- As suggested by Linus, replaced 'tsk->comm' with 'tsk->comm_str' locally, and verified basic
  thread names and then changed 'tsk->comm_str' back to 'tsk->comm'. So essentially now 'tsk->comm'
  is TASK_COMM_EXT_LEN i.e. 64-bytes long.

Changes since v4:
================
- v4 can be seen here: https://lore.kernel.org/lkml/20250521062337.53262-1-bhupesh@igalia.com/ 
- As suggested by Kees, replaced tsk->comm with tsk->comm_str, inside 'task_struct'
  where TASK_COMM_EXT_LEN is 64-bytes.

Changes since v3:
================
- v3 can be seen here: https://lore.kernel.org/lkml/20250507110444.963779-1-bhupesh@igalia.com/
- As suggested by Petr and Steven, used 'comm_ext' name instead of
  'real_comm'. Correspondingly the macro name is changed to 'TASK_COMM_EXT_LEN'
  for the 64-byte extended comm.
- Rebased this patchset on linux-next/master, which contain the following patch from
  Steven now:
       155fd6c3e2f0 ("tracing/sched: Use __string() instead of fixed lengths for task->comm")
- Accordingly, v4 drops the changes done for 'trace/sched' events in v3,
  but retains the 'safe' memcpy' changes for other kernel trace users.

Changes since v2:
================
- v2 can be seen here: https://lore.kernel.org/lkml/20250331121820.455916-1-bhupesh@igalia.com/
- As suggested by Yafang and Kees, picked Linus' suggested approach for
  this version (see: <https://lore.kernel.org/all/CAHk-=wjAmmHUg6vho1KjzQi2=psR30+CogFd4aXrThr2gsiS4g@mail.gmail.com/>).
- Dropped kthreads patch from this version. It would be sent out
  separately, if we have a consensus on this approach.

Changes since v1:
================
- v1 can be seen here: https://lore.kernel.org/lkml/20250314052715.610377-1-bhupesh@igalia.com/
- As suggested by Kees, added [PATCH 3/3] to have a consistent
  'full_name' entry inside 'task_struct' which both tasks and
  kthreads can use.
- Fixed the commit message to indicate that the existing ABI
  '/proc/$pid/task/$tid/comm' remains untouched and a parallel
  '/proc/$pid/task/$tid/full_name' ABI for new (interested) users.

While working with user-space debugging tools which work especially
on linux gaming platforms, I found that the task name is truncated due
to the limitation of TASK_COMM_LEN.

Now, during debug tracing, seeing truncated names is not very useful,
especially on gaming platforms where the number of tasks running can
be very high.

This patchset does not touch 'TASK_COMM_LEN' at all, i.e.
'TASK_COMM_LEN' and the 16-byte design remains untouched.

Via this patchset, Linus suggested 'tsk->comm' is made 64-byte long
and equal to TASK_COMM_EXT_LEN.

To avoid any surprises / bug,s I replaced 'tsk->comm' with
'tsk->comm_str' locally inside 'task_struct' and checked compilation
of code and basic working of thread names:

       struct task_struct {
	       ..............
               char    comm_str[TASK_COMM_EXT_LEN];
	       ..............
       };

       where TASK_COMM_EXT_LEN is 64-bytes.

Once done, I changed the name back to 'tsk->comm'.

To ensure that the existing ABI and userspace continues to work
as intended, we ensure that:

- Existing users of 'get_task_comm'/ 'set_task_comm' will get 'tsk->comm'
  truncated to a maximum of 'TASK_COMM_LEN' (16-bytes) to maintain ABI,
- New / Modified users of 'get_task_comm'/ 'set_task_comm' will get
 'tsk->comm' supported up to a maximum of 'TASK_COMM_EXT_LEN' (64-bytes).

Note, that the existing users have not been modified to migrate to
'TASK_COMM_EXT_LEN', in case they have hard-coded expectations of
dealing with only a 'TASK_COMM_LEN' long 'tsk->comm_str'.

After this change, gdb is able to show full name of the task, using a
simple app which generates threads with long names [see 1]:
  # gdb ./threadnames -ex "run info thread" -ex "detach" -ex "quit" > log
  # cat log

  NameThatIsTooLongForComm[4662]

[1]. https://github.com/lostgoat/tasknames

Bhupesh (4):
  exec: Remove obsolete comments
  include: Set tsk->comm length to 64 bytes
  treewide: Replace 'get_task_comm()' with 'strscpy_pad()'
  treewide: Switch memcpy() users of 'task->comm' to a more safer
    implementation

 drivers/connector/cn_proc.c                   |  2 +-
 drivers/dma-buf/sw_sync.c                     |  2 +-
 .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c  |  2 +-
 .../drm/amd/amdgpu/amdgpu_eviction_fence.c    |  2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c       |  2 +-
 .../gpu/drm/amd/amdgpu/amdgpu_userq_fence.c   |  2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c        |  4 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c  |  2 +-
 drivers/gpu/drm/lima/lima_ctx.c               |  2 +-
 drivers/gpu/drm/panfrost/panfrost_gem.c       |  2 +-
 drivers/gpu/drm/panthor/panthor_gem.c         |  2 +-
 drivers/gpu/drm/virtio/virtgpu_ioctl.c        |  2 +-
 drivers/hwtracing/stm/core.c                  |  2 +-
 drivers/tty/tty_audit.c                       |  2 +-
 fs/bcachefs/thread_with_file.c                |  2 +-
 fs/binfmt_elf.c                               |  2 +-
 fs/binfmt_elf_fdpic.c                         |  2 +-
 fs/ocfs2/cluster/netdebug.c                   |  1 -
 fs/proc/array.c                               |  2 +-
 include/linux/coredump.h                      |  2 +-
 include/linux/sched.h                         | 50 ++++++++++++-------
 include/linux/tracepoint.h                    |  4 +-
 include/trace/events/block.h                  | 10 ++--
 include/trace/events/oom.h                    |  2 +-
 include/trace/events/osnoise.h                |  2 +-
 include/trace/events/sched.h                  | 13 +++--
 include/trace/events/signal.h                 |  2 +-
 include/trace/events/task.h                   |  4 +-
 kernel/audit.c                                |  6 ++-
 kernel/auditsc.c                              |  6 ++-
 kernel/sys.c                                  |  2 +-
 mm/kmemleak.c                                 |  6 ---
 net/bluetooth/hci_sock.c                      |  2 +-
 net/netfilter/nf_tables_api.c                 |  2 +-
 security/integrity/integrity_audit.c          |  3 +-
 security/ipe/audit.c                          |  2 +-
 security/landlock/domain.c                    |  2 +-
 security/lsm_audit.c                          |  7 +--
 tools/bpf/bpftool/pids.c                      |  6 +--
 .../bpf/test_kmods/bpf_testmod-events.h       |  2 +-
 40 files changed, 91 insertions(+), 83 deletions(-)

-- 
2.38.1

[PATCH v7 1/4] exec: Remove obsolete comments

[Bhupesh]

Patch 3a3f61ce5e0b ("exec: Make sure task->comm is always NUL-terminated"),
replaced 'strscpy_pad()' with 'memcpy()' implementations inside
'__set_task_comm()'.

However a few left-over comments are still there, which mention
the usage of 'strscpy_pad()' inside '__set_task_comm()'.

Remove those obsolete comments.

While at it, also remove an obsolete comment regarding 'task_lock()'
usage while handing 'task->comm'.

Signed-off-by: Bhupesh <bhupesh@igalia.com>
Reviewed-by: Kees Cook <kees@kernel.org>
---
 include/linux/sched.h | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 2b272382673d..35f1ef06eb6c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1159,10 +1159,8 @@ struct task_struct {
 	 *
 	 * - normally initialized begin_new_exec()
 	 * - set it with set_task_comm()
-	 *   - strscpy_pad() to ensure it is always NUL-terminated and
+	 *   - logic inside set_task_comm() will ensure it is always NUL-terminated and
 	 *     zero-padded
-	 *   - task_lock() to ensure the operation is atomic and the name is
-	 *     fully updated.
 	 */
 	char				comm[TASK_COMM_LEN];
 
@@ -1972,7 +1970,7 @@ extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec
  *   User space can randomly change their names anyway, so locking for readers
  *   doesn't make sense. For writers, locking is probably necessary, as a race
  *   condition could lead to long-term mixed results.
- *   The strscpy_pad() in __set_task_comm() can ensure that the task comm is
+ *   The logic inside __set_task_comm() should ensure that the task comm is
  *   always NUL-terminated and zero-padded. Therefore the race condition between
  *   reader and writer is not an issue.
  *
-- 
2.38.1

[PATCH v7 2/4] include: Set tsk->comm length to 64 bytes

[Bhupesh]

Historically due to the 16-byte length of TASK_COMM_LEN, the
users of 'tsk->comm' are restricted to use a fixed-size target
buffer also of TASK_COMM_LEN for 'memcpy()' like use-cases.

To fix the same, we now use a 64-byte TASK_COMM_EXT_LEN and
set the comm element inside 'task_struct' to the same length:
       struct task_struct {
	       .....
               char    comm[TASK_COMM_EXT_LEN];
	       .....
       };

       where TASK_COMM_EXT_LEN is 64-bytes.

Note, that the existing users have not been modified to migrate to
'TASK_COMM_EXT_LEN', in case they have hard-coded expectations of
dealing with only a 'TASK_COMM_LEN' long 'tsk->comm'.

Signed-off-by: Bhupesh <bhupesh@igalia.com>
---
 include/linux/sched.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 35f1ef06eb6c..87e9dfaf61ac 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -318,6 +318,7 @@ struct user_event_mm;
  */
 enum {
 	TASK_COMM_LEN = 16,
+	TASK_COMM_EXT_LEN = 64,
 };
 
 extern void sched_tick(void);
@@ -1162,7 +1163,7 @@ struct task_struct {
 	 *   - logic inside set_task_comm() will ensure it is always NUL-terminated and
 	 *     zero-padded
 	 */
-	char				comm[TASK_COMM_LEN];
+	char				comm[TASK_COMM_EXT_LEN];
 
 	struct nameidata		*nameidata;
 
@@ -1961,7 +1962,7 @@ extern void kick_process(struct task_struct *tsk);
 
 extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec);
 #define set_task_comm(tsk, from) ({			\
-	BUILD_BUG_ON(sizeof(from) != TASK_COMM_LEN);	\
+	BUILD_BUG_ON(sizeof(from) < TASK_COMM_LEN);	\
 	__set_task_comm(tsk, from, false);		\
 })
 
-- 
2.38.1

Re: [PATCH v7 2/4] include: Set tsk->comm length to 64 bytes

[Andy Shevchenko]

On Mon, Aug 11, 2025 at 12:16:07PM +0530, Bhupesh wrote:
> Historically due to the 16-byte length of TASK_COMM_LEN, the
> users of 'tsk->comm' are restricted to use a fixed-size target
> buffer also of TASK_COMM_LEN for 'memcpy()' like use-cases.
> 
> To fix the same, we now use a 64-byte TASK_COMM_EXT_LEN and
> set the comm element inside 'task_struct' to the same length:
>        struct task_struct {
> 	       .....
>                char    comm[TASK_COMM_EXT_LEN];
> 	       .....
>        };
> 
>        where TASK_COMM_EXT_LEN is 64-bytes.
> 
> Note, that the existing users have not been modified to migrate to
> 'TASK_COMM_EXT_LEN', in case they have hard-coded expectations of
> dealing with only a 'TASK_COMM_LEN' long 'tsk->comm'.

...

> -	BUILD_BUG_ON(sizeof(from) != TASK_COMM_LEN);	\
> +	BUILD_BUG_ON(sizeof(from) < TASK_COMM_LEN);	\

Wondering if we may convert this to static_assert().
(rather in a separate patch)

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v7 2/4] include: Set tsk->comm length to 64 bytes

[Bhupesh Sharma]

On 8/11/25 8:40 PM, Andy Shevchenko wrote:
> On Mon, Aug 11, 2025 at 12:16:07PM +0530, Bhupesh wrote:
>> Historically due to the 16-byte length of TASK_COMM_LEN, the
>> users of 'tsk->comm' are restricted to use a fixed-size target
>> buffer also of TASK_COMM_LEN for 'memcpy()' like use-cases.
>>
>> To fix the same, we now use a 64-byte TASK_COMM_EXT_LEN and
>> set the comm element inside 'task_struct' to the same length:
>>         struct task_struct {
>> 	       .....
>>                 char    comm[TASK_COMM_EXT_LEN];
>> 	       .....
>>         };
>>
>>         where TASK_COMM_EXT_LEN is 64-bytes.
>>
>> Note, that the existing users have not been modified to migrate to
>> 'TASK_COMM_EXT_LEN', in case they have hard-coded expectations of
>> dealing with only a 'TASK_COMM_LEN' long 'tsk->comm'.
> ...
>
>> -	BUILD_BUG_ON(sizeof(from) != TASK_COMM_LEN);	\
>> +	BUILD_BUG_ON(sizeof(from) < TASK_COMM_LEN);	\
> Wondering if we may convert this to static_assert().
> (rather in a separate patch)

That's a fair suggestion. If others don't have an objection to the 
suggested change, I can club it in v8 along with any other requested 
changes.

Thanks.

[PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'

[Bhupesh]

As Linus mentioned in [1], we should get rid of 'get_task_comm()'
entirely and replace it with 'strscpy_pad()' implementation.

'strscpy_pad()' will already make sure comm is NUL-terminated, so
we won't need the explicit final byte termination done in
'get_task_comm()'.

The relevant 'get_task_comm()' users were identified using the
following search pattern:
 $ git grep 'get_task_comm*'

[1]. https://lore.kernel.org/all/CAHk-=wi5c=_-FBGo_88CowJd_F-Gi6Ud9d=TALm65ReN7YjrMw@mail.gmail.com/

Signed-off-by: Bhupesh <bhupesh@igalia.com>
---
 drivers/connector/cn_proc.c                   |  2 +-
 drivers/dma-buf/sw_sync.c                     |  2 +-
 .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c  |  2 +-
 .../drm/amd/amdgpu/amdgpu_eviction_fence.c    |  2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c       |  2 +-
 .../gpu/drm/amd/amdgpu/amdgpu_userq_fence.c   |  2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c        |  4 ++--
 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c  |  2 +-
 drivers/gpu/drm/lima/lima_ctx.c               |  2 +-
 drivers/gpu/drm/panfrost/panfrost_gem.c       |  2 +-
 drivers/gpu/drm/panthor/panthor_gem.c         |  2 +-
 drivers/gpu/drm/virtio/virtgpu_ioctl.c        |  2 +-
 drivers/hwtracing/stm/core.c                  |  2 +-
 drivers/tty/tty_audit.c                       |  2 +-
 fs/bcachefs/thread_with_file.c                |  2 +-
 fs/binfmt_elf.c                               |  2 +-
 fs/binfmt_elf_fdpic.c                         |  2 +-
 fs/ocfs2/cluster/netdebug.c                   |  1 -
 fs/proc/array.c                               |  2 +-
 include/linux/sched.h                         | 19 -------------------
 kernel/audit.c                                |  6 ++++--
 kernel/auditsc.c                              |  6 ++++--
 kernel/sys.c                                  |  2 +-
 mm/kmemleak.c                                 |  6 ------
 net/bluetooth/hci_sock.c                      |  2 +-
 net/netfilter/nf_tables_api.c                 |  2 +-
 security/integrity/integrity_audit.c          |  3 ++-
 security/ipe/audit.c                          |  2 +-
 security/landlock/domain.c                    |  2 +-
 security/lsm_audit.c                          |  7 ++++---
 30 files changed, 38 insertions(+), 58 deletions(-)

diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
index 44b19e696176..3c1b07198e10 100644
--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -278,7 +278,7 @@ void proc_comm_connector(struct task_struct *task)
 	ev->what = PROC_EVENT_COMM;
 	ev->event_data.comm.process_pid  = task->pid;
 	ev->event_data.comm.process_tgid = task->tgid;
-	get_task_comm(ev->event_data.comm.comm, task);
+	strscpy_pad(ev->event_data.comm.comm, task->comm);
 
 	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 	msg->ack = 0; /* not used */
diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c
index 3c20f1d31cf5..1f2ddf00799b 100644
--- a/drivers/dma-buf/sw_sync.c
+++ b/drivers/dma-buf/sw_sync.c
@@ -311,7 +311,7 @@ static int sw_sync_debugfs_open(struct inode *inode, struct file *file)
 	struct sync_timeline *obj;
 	char task_comm[TASK_COMM_LEN];
 
-	get_task_comm(task_comm, current);
+	strscpy_pad(task_comm, current->comm);
 
 	obj = sync_timeline_create(task_comm);
 	if (!obj)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
index 1ef758ac5076..ea2b99fde425 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
@@ -73,7 +73,7 @@ struct amdgpu_amdkfd_fence *amdgpu_amdkfd_fence_create(u64 context,
 	/* This reference gets released in amdkfd_fence_release */
 	mmgrab(mm);
 	fence->mm = mm;
-	get_task_comm(fence->timeline_name, current);
+	strscpy_pad(fence->timeline_name, current->comm);
 	spin_lock_init(&fence->lock);
 	fence->svm_bo = svm_bo;
 	dma_fence_init(&fence->base, &amdkfd_fence_ops, &fence->lock,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_eviction_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_eviction_fence.c
index 23d7d0b0d625..3e2ad72cafc4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_eviction_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_eviction_fence.c
@@ -166,7 +166,7 @@ amdgpu_eviction_fence_create(struct amdgpu_eviction_fence_mgr *evf_mgr)
 		return NULL;
 
 	ev_fence->evf_mgr = evf_mgr;
-	get_task_comm(ev_fence->timeline_name, current);
+	strscpy_pad(ev_fence->timeline_name, current->comm);
 	spin_lock_init(&ev_fence->lock);
 	dma_fence_init64(&ev_fence->base, &amdgpu_eviction_fence_ops,
 			 &ev_fence->lock, evf_mgr->ev_fence_ctx,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
index 25bade9a5e95..8a4a4c03bbcd 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
@@ -4169,7 +4169,7 @@ int amdgpu_ras_init(struct amdgpu_device *adev)
 	}
 
 	con->init_task_pid = task_pid_nr(current);
-	get_task_comm(con->init_task_comm, current);
+	strscpy_pad(con->init_task_comm, current->comm);
 
 	mutex_init(&con->critical_region_lock);
 	INIT_LIST_HEAD(&con->critical_region_head);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
index c2a983ff23c9..73aa37f65e0b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
@@ -92,7 +92,7 @@ int amdgpu_userq_fence_driver_alloc(struct amdgpu_device *adev,
 
 	fence_drv->adev = adev;
 	fence_drv->context = dma_fence_context_alloc(1);
-	get_task_comm(fence_drv->timeline_name, current);
+	strscpy_pad(fence_drv->timeline_name, current->comm);
 
 	xa_lock_irqsave(&adev->userq_xa, flags);
 	r = xa_err(__xa_store(&adev->userq_xa, userq->doorbell_index,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 39b4250ede0f..83b5d5f5775c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -2516,13 +2516,13 @@ void amdgpu_vm_set_task_info(struct amdgpu_vm *vm)
 		return;
 
 	vm->task_info->task.pid = current->pid;
-	get_task_comm(vm->task_info->task.comm, current);
+	strscpy_pad(vm->task_info->task.comm, current->comm);
 
 	if (current->group_leader->mm != current->mm)
 		return;
 
 	vm->task_info->tgid = current->group_leader->pid;
-	get_task_comm(vm->task_info->process_name, current->group_leader);
+	strscpy_pad(vm->task_info->process_name, current->group_leader->comm);
 }
 
 /**
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index 77ce9cf28051..7e2f0d28b7ef 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -598,7 +598,7 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 	}
 
 	vres->task.pid = task_pid_nr(current);
-	get_task_comm(vres->task.comm, current);
+	strscpy_pad(vres->task.comm, current->comm);
 	list_add_tail(&vres->vres_node, &mgr->allocated_vres_list);
 
 	if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS && adjust_dcc_size) {
diff --git a/drivers/gpu/drm/lima/lima_ctx.c b/drivers/gpu/drm/lima/lima_ctx.c
index 0e668fc1e0f9..7536288ec93b 100644
--- a/drivers/gpu/drm/lima/lima_ctx.c
+++ b/drivers/gpu/drm/lima/lima_ctx.c
@@ -29,7 +29,7 @@ int lima_ctx_create(struct lima_device *dev, struct lima_ctx_mgr *mgr, u32 *id)
 		goto err_out0;
 
 	ctx->pid = task_pid_nr(current);
-	get_task_comm(ctx->pname, current);
+	strscpy_pad(ctx->pname, current->comm);
 
 	return 0;
 
diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
index bb73f2a68a12..b6575fc43ee4 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
@@ -17,7 +17,7 @@ static void panfrost_gem_debugfs_bo_add(struct panfrost_device *pfdev,
 					struct panfrost_gem_object *bo)
 {
 	bo->debugfs.creator.tgid = current->group_leader->pid;
-	get_task_comm(bo->debugfs.creator.process_name, current->group_leader);
+	strscpy_pad(bo->debugfs.creator.process_name, current->group_leader->comm);
 
 	mutex_lock(&pfdev->debugfs.gems_lock);
 	list_add_tail(&bo->debugfs.node, &pfdev->debugfs.gems_list);
diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
index a123bc740ba1..ba2b80c760c9 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.c
+++ b/drivers/gpu/drm/panthor/panthor_gem.c
@@ -27,7 +27,7 @@ static void panthor_gem_debugfs_bo_add(struct panthor_gem_object *bo)
 						    struct panthor_device, base);
 
 	bo->debugfs.creator.tgid = current->group_leader->pid;
-	get_task_comm(bo->debugfs.creator.process_name, current->group_leader);
+	strscpy_pad(bo->debugfs.creator.process_name, current->group_leader->comm);
 
 	mutex_lock(&ptdev->gems.lock);
 	list_add_tail(&bo->debugfs.node, &ptdev->gems.node);
diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index c33c057365f8..d2bf221e8f01 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -50,7 +50,7 @@ static void virtio_gpu_create_context_locked(struct virtio_gpu_device *vgdev,
 	} else {
 		char dbgname[TASK_COMM_LEN];
 
-		get_task_comm(dbgname, current);
+		strscpy_pad(dbgname, current->comm);
 		virtio_gpu_cmd_context_create(vgdev, vfpriv->ctx_id,
 					      vfpriv->context_init, strlen(dbgname),
 					      dbgname);
diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index cdba4e875b28..f07784c8751c 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -634,7 +634,7 @@ static ssize_t stm_char_write(struct file *file, const char __user *buf,
 		char comm[sizeof(current->comm)];
 		char *ids[] = { comm, "default", NULL };
 
-		get_task_comm(comm, current);
+		strscpy_pad(comm, current->comm);
 
 		err = stm_assign_first_policy(stmf->stm, &stmf->output, ids, 1);
 		/*
diff --git a/drivers/tty/tty_audit.c b/drivers/tty/tty_audit.c
index 75542333c54a..2724341edda0 100644
--- a/drivers/tty/tty_audit.c
+++ b/drivers/tty/tty_audit.c
@@ -77,7 +77,7 @@ static void tty_audit_log(const char *description, dev_t dev,
 	audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d minor=%d comm=",
 			 description, pid, uid, loginuid, sessionid,
 			 MAJOR(dev), MINOR(dev));
-	get_task_comm(name, current);
+	strscpy_pad(name, current->comm);
 	audit_log_untrustedstring(ab, name);
 	audit_log_format(ab, " data=");
 	audit_log_n_hex(ab, data, size);
diff --git a/fs/bcachefs/thread_with_file.c b/fs/bcachefs/thread_with_file.c
index c2eae0ab7765..eda1b6b5e3b7 100644
--- a/fs/bcachefs/thread_with_file.c
+++ b/fs/bcachefs/thread_with_file.c
@@ -35,7 +35,7 @@ int bch2_run_thread_with_file(struct thread_with_file *thr,
 		fd_flags |= O_WRONLY;
 
 	char name[TASK_COMM_LEN];
-	get_task_comm(name, current);
+	strscpy_pad(name, current->comm);
 
 	thr->ret = 0;
 	thr->task = kthread_create(fn, thr, "%s", name);
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 264fba0d44bd..6ea946656403 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1540,7 +1540,7 @@ static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p,
 	SET_UID(psinfo->pr_uid, from_kuid_munged(cred->user_ns, cred->uid));
 	SET_GID(psinfo->pr_gid, from_kgid_munged(cred->user_ns, cred->gid));
 	rcu_read_unlock();
-	get_task_comm(psinfo->pr_fname, p);
+	strscpy_pad(psinfo->pr_fname, p->comm);
 
 	return 0;
 }
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 48fd2de3bca0..605d09d3c36f 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1365,7 +1365,7 @@ static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p,
 	SET_UID(psinfo->pr_uid, from_kuid_munged(cred->user_ns, cred->uid));
 	SET_GID(psinfo->pr_gid, from_kgid_munged(cred->user_ns, cred->gid));
 	rcu_read_unlock();
-	get_task_comm(psinfo->pr_fname, p);
+	strscpy_pad(psinfo->pr_fname, p->comm);
 
 	return 0;
 }
diff --git a/fs/ocfs2/cluster/netdebug.c b/fs/ocfs2/cluster/netdebug.c
index bc27301eab6d..ab94ab55111e 100644
--- a/fs/ocfs2/cluster/netdebug.c
+++ b/fs/ocfs2/cluster/netdebug.c
@@ -122,7 +122,6 @@ static int nst_seq_show(struct seq_file *seq, void *v)
 	send = ktime_to_us(ktime_sub(now, nst->st_send_time));
 	status = ktime_to_us(ktime_sub(now, nst->st_status_time));
 
-	/* get_task_comm isn't exported.  oh well. */
 	seq_printf(seq, "%p:\n"
 		   "  pid:          %lu\n"
 		   "  tgid:         %lu\n"
diff --git a/fs/proc/array.c b/fs/proc/array.c
index d6a0369caa93..c65a4c2994c2 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -109,7 +109,7 @@ void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
 	else if (p->flags & PF_KTHREAD)
 		get_kthread_comm(tcomm, sizeof(tcomm), p);
 	else
-		get_task_comm(tcomm, p);
+		strscpy_pad(tcomm, p->comm);
 
 	if (escape)
 		seq_escape_str(m, tcomm, ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 87e9dfaf61ac..97ea2ac2a97a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1966,25 +1966,6 @@ extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec
 	__set_task_comm(tsk, from, false);		\
 })
 
-/*
- * - Why not use task_lock()?
- *   User space can randomly change their names anyway, so locking for readers
- *   doesn't make sense. For writers, locking is probably necessary, as a race
- *   condition could lead to long-term mixed results.
- *   The logic inside __set_task_comm() should ensure that the task comm is
- *   always NUL-terminated and zero-padded. Therefore the race condition between
- *   reader and writer is not an issue.
- *
- * - BUILD_BUG_ON() can help prevent the buf from being truncated.
- *   Since the callers don't perform any return value checks, this safeguard is
- *   necessary.
- */
-#define get_task_comm(buf, tsk) ({			\
-	BUILD_BUG_ON(sizeof(buf) < TASK_COMM_LEN);	\
-	strscpy_pad(buf, (tsk)->comm);			\
-	buf;						\
-})
-
 static __always_inline void scheduler_ipi(void)
 {
 	/*
diff --git a/kernel/audit.c b/kernel/audit.c
index 61b5744d0bb6..64623f186fc6 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1621,7 +1621,8 @@ static void audit_log_multicast(int group, const char *op, int err)
 	audit_put_tty(tty);
 	audit_log_task_context(ab); /* subj= */
 	audit_log_format(ab, " comm=");
-	audit_log_untrustedstring(ab, get_task_comm(comm, current));
+	strscpy_pad(comm, current->comm);
+	audit_log_untrustedstring(ab, comm);
 	audit_log_d_path_exe(ab, current->mm); /* exe= */
 	audit_log_format(ab, " nl-mcgrp=%d op=%s res=%d", group, op, !err);
 	audit_log_end(ab);
@@ -2270,7 +2271,8 @@ void audit_log_task_info(struct audit_buffer *ab)
 			 audit_get_sessionid(current));
 	audit_put_tty(tty);
 	audit_log_format(ab, " comm=");
-	audit_log_untrustedstring(ab, get_task_comm(comm, current));
+	strscpy_pad(comm, current->comm);
+	audit_log_untrustedstring(ab, comm);
 	audit_log_d_path_exe(ab, current->mm);
 	audit_log_task_context(ab);
 }
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index eb98cd6fe91f..67a132114329 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2930,7 +2930,8 @@ void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries,
 	audit_log_format(ab, " pid=%u", task_tgid_nr(current));
 	audit_log_task_context(ab); /* subj= */
 	audit_log_format(ab, " comm=");
-	audit_log_untrustedstring(ab, get_task_comm(comm, current));
+	strscpy_pad(comm, current->comm);
+	audit_log_untrustedstring(ab, comm);
 	audit_log_end(ab);
 }
 EXPORT_SYMBOL_GPL(__audit_log_nfcfg);
@@ -2953,7 +2954,8 @@ static void audit_log_task(struct audit_buffer *ab)
 			 sessionid);
 	audit_log_task_context(ab);
 	audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
-	audit_log_untrustedstring(ab, get_task_comm(comm, current));
+	strscpy_pad(comm, current->comm);
+	audit_log_untrustedstring(ab, comm);
 	audit_log_d_path_exe(ab, current->mm);
 }
 
diff --git a/kernel/sys.c b/kernel/sys.c
index 0d5d27cb9cbe..cb5cce753e71 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2535,7 +2535,7 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 		proc_comm_connector(me);
 		break;
 	case PR_GET_NAME:
-		get_task_comm(comm, me);
+		strscpy_pad(comm, me->comm);
 		if (copy_to_user((char __user *)arg2, comm, sizeof(comm)))
 			return -EFAULT;
 		break;
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 84265983f239..42e67c03cb7d 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -682,12 +682,6 @@ static struct kmemleak_object *__alloc_object(gfp_t gfp)
 		strscpy(object->comm, "softirq");
 	} else {
 		object->pid = current->pid;
-		/*
-		 * There is a small chance of a race with set_task_comm(),
-		 * however using get_task_comm() here may cause locking
-		 * dependency issues with current->alloc_lock. In the worst
-		 * case, the command line is not correct.
-		 */
 		strscpy(object->comm, current->comm);
 	}
 
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index fc866759910d..759a508024be 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -106,7 +106,7 @@ static bool hci_sock_gen_cookie(struct sock *sk)
 			id = 0xffffffff;
 
 		hci_pi(sk)->cookie = id;
-		get_task_comm(hci_pi(sk)->comm, current);
+		strscpy_pad(hci_pi(sk)->comm, current->comm);
 		return true;
 	}
 
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 13d0ed9d1895..e3a73ca4e9c3 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -9658,7 +9658,7 @@ static int nf_tables_fill_gen_info(struct sk_buff *skb, struct net *net,
 
 	if (nla_put_be32(skb, NFTA_GEN_ID, htonl(nft_net->base_seq)) ||
 	    nla_put_be32(skb, NFTA_GEN_PROC_PID, htonl(task_pid_nr(current))) ||
-	    nla_put_string(skb, NFTA_GEN_PROC_NAME, get_task_comm(buf, current)))
+	    nla_put_string(skb, NFTA_GEN_PROC_NAME, strscpy_pad(buf, current->comm)))
 		goto nla_put_failure;
 
 	nlmsg_end(skb, nlh);
diff --git a/security/integrity/integrity_audit.c b/security/integrity/integrity_audit.c
index 0ec5e4c22cb2..28c203f0cdb7 100644
--- a/security/integrity/integrity_audit.c
+++ b/security/integrity/integrity_audit.c
@@ -54,7 +54,8 @@ void integrity_audit_message(int audit_msgno, struct inode *inode,
 			 audit_get_sessionid(current));
 	audit_log_task_context(ab);
 	audit_log_format(ab, " op=%s cause=%s comm=", op, cause);
-	audit_log_untrustedstring(ab, get_task_comm(name, current));
+	strscpy_pad(name, current->comm);
+	audit_log_untrustedstring(ab, name);
 	if (fname) {
 		audit_log_format(ab, " name=");
 		audit_log_untrustedstring(ab, fname);
diff --git a/security/ipe/audit.c b/security/ipe/audit.c
index de5fed62592e..b4318988c65d 100644
--- a/security/ipe/audit.c
+++ b/security/ipe/audit.c
@@ -144,7 +144,7 @@ void ipe_audit_match(const struct ipe_eval_ctx *const ctx,
 	audit_log_format(ab, "ipe_op=%s ipe_hook=%s enforcing=%d pid=%d comm=",
 			 op, audit_hook_names[ctx->hook], READ_ONCE(enforce),
 			 task_tgid_nr(current));
-	audit_log_untrustedstring(ab, get_task_comm(comm, current));
+	audit_log_untrustedstring(ab, strscpy_pad(comm, current->comm));
 
 	if (ctx->file) {
 		audit_log_d_path(ab, " path=", &ctx->file->f_path);
diff --git a/security/landlock/domain.c b/security/landlock/domain.c
index a647b68e8d06..77b678f0f469 100644
--- a/security/landlock/domain.c
+++ b/security/landlock/domain.c
@@ -102,7 +102,7 @@ static struct landlock_details *get_current_details(void)
 	memcpy(details->exe_path, path_str, path_size);
 	details->pid = get_pid(task_tgid(current));
 	details->uid = from_kuid(&init_user_ns, current_uid());
-	get_task_comm(details->comm, current);
+	strscpy_pad(details->comm, current->comm);
 	return details;
 }
 
diff --git a/security/lsm_audit.c b/security/lsm_audit.c
index 7d623b00495c..b4d3b8a69cfe 100644
--- a/security/lsm_audit.c
+++ b/security/lsm_audit.c
@@ -276,8 +276,8 @@ void audit_log_lsm_data(struct audit_buffer *ab,
 			if (pid) {
 				char tskcomm[sizeof(tsk->comm)];
 				audit_log_format(ab, " opid=%d ocomm=", pid);
-				audit_log_untrustedstring(ab,
-				    get_task_comm(tskcomm, tsk));
+				strscpy_pad(tskcomm, tsk->comm);
+				audit_log_untrustedstring(ab, tskcomm);
 			}
 		}
 		break;
@@ -417,7 +417,8 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 	char comm[sizeof(current->comm)];
 
 	audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
-	audit_log_untrustedstring(ab, get_task_comm(comm, current));
+	strscpy_pad(comm, current->comm);
+	audit_log_untrustedstring(ab, comm);
 	audit_log_lsm_data(ab, a);
 }
 
-- 
2.38.1

Re: [PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'

[kernel test robot]

Hi Bhupesh,

kernel test robot noticed the following build errors:

[auto build test ERROR on next-20250808]
[cannot apply to trace/for-next tip/sched/core brauner-vfs/vfs.all linus/master v6.17-rc1 v6.16 v6.16-rc7 v6.17-rc1]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Bhupesh/exec-Remove-obsolete-comments/20250811-144920
base:   next-20250808
patch link:    https://lore.kernel.org/r/20250811064609.918593-4-bhupesh%40igalia.com
patch subject: [PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'
config: sh-randconfig-002-20250811 (https://download.01.org/0day-ci/archive/20250811/202508111835.JFL8DgKY-lkp@intel.com/config)
compiler: sh4-linux-gcc (GCC) 15.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250811/202508111835.JFL8DgKY-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202508111835.JFL8DgKY-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from include/linux/bitmap.h:13,
                    from include/linux/cpumask.h:12,
                    from include/linux/smp.h:13,
                    from include/linux/lockdep.h:14,
                    from include/linux/spinlock.h:63,
                    from include/linux/mmzone.h:8,
                    from include/linux/gfp.h:7,
                    from include/linux/umh.h:4,
                    from include/linux/kmod.h:9,
                    from include/linux/module.h:18,
                    from net/netfilter/nf_tables_api.c:8:
   net/netfilter/nf_tables_api.c: In function 'nf_tables_fill_gen_info':
>> include/linux/string.h:116:50: error: passing argument 3 of 'nla_put_string' makes pointer from integer without a cast [-Wint-conversion]
     116 | #define sized_strscpy_pad(dest, src, count)     ({                      \
         |                                                 ~^~~~~~~~~~~~~~~~~~~~~~~~
         |                                                  |
         |                                                  ssize_t {aka int}
     117 |         char *__dst = (dest);                                           \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     118 |         const char *__src = (src);                                      \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     119 |         const size_t __count = (count);                                 \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     120 |         ssize_t __wrote;                                                \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     121 |                                                                         \
         |                                                                         ~
     122 |         __wrote = sized_strscpy(__dst, __src, __count);                 \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     123 |         if (__wrote >= 0 && __wrote < __count)                          \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     124 |                 memset(__dst + __wrote + 1, 0, __count - __wrote - 1);  \
         |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     125 |         __wrote;                                                        \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     126 | })
         | ~~                                                
   include/linux/string.h:86:9: note: in expansion of macro 'sized_strscpy_pad'
      86 |         sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) +        \
         |         ^~~~~~~~~~~~~~~~~
   include/linux/args.h:25:24: note: in expansion of macro '__strscpy_pad0'
      25 | #define __CONCAT(a, b) a ## b
         |                        ^
   include/linux/args.h:26:27: note: in expansion of macro '__CONCAT'
      26 | #define CONCATENATE(a, b) __CONCAT(a, b)
         |                           ^~~~~~~~
   include/linux/string.h:149:9: note: in expansion of macro 'CONCATENATE'
     149 |         CONCATENATE(__strscpy_pad, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
         |         ^~~~~~~~~~~
   net/netfilter/nf_tables_api.c:9661:53: note: in expansion of macro 'strscpy_pad'
    9661 |             nla_put_string(skb, NFTA_GEN_PROC_NAME, strscpy_pad(buf, current->comm)))
         |                                                     ^~~~~~~~~~~
   In file included from include/linux/netfilter/nfnetlink.h:7,
                    from net/netfilter/nf_tables_api.c:17:
   include/net/netlink.h:1655:46: note: expected 'const char *' but argument is of type 'ssize_t' {aka 'int'}
    1655 |                                  const char *str)
         |                                  ~~~~~~~~~~~~^~~


vim +/nla_put_string +116 include/linux/string.h

e6584c3964f2ff Kees Cook        2023-09-20   74  
e6584c3964f2ff Kees Cook        2023-09-20   75  /*
e6584c3964f2ff Kees Cook        2023-09-20   76   * The 2 argument style can only be used when dst is an array with a
e6584c3964f2ff Kees Cook        2023-09-20   77   * known size.
e6584c3964f2ff Kees Cook        2023-09-20   78   */
e6584c3964f2ff Kees Cook        2023-09-20   79  #define __strscpy0(dst, src, ...)	\
559048d156ff33 Kees Cook        2024-08-05   80  	sized_strscpy(dst, src, sizeof(dst) + __must_be_array(dst) +	\
559048d156ff33 Kees Cook        2024-08-05   81  				__must_be_cstr(dst) + __must_be_cstr(src))
559048d156ff33 Kees Cook        2024-08-05   82  #define __strscpy1(dst, src, size)	\
559048d156ff33 Kees Cook        2024-08-05   83  	sized_strscpy(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src))
e6584c3964f2ff Kees Cook        2023-09-20   84  
8366d124ec937c Kees Cook        2024-02-02   85  #define __strscpy_pad0(dst, src, ...)	\
559048d156ff33 Kees Cook        2024-08-05   86  	sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) +	\
559048d156ff33 Kees Cook        2024-08-05   87  				    __must_be_cstr(dst) + __must_be_cstr(src))
559048d156ff33 Kees Cook        2024-08-05   88  #define __strscpy_pad1(dst, src, size)	\
559048d156ff33 Kees Cook        2024-08-05   89  	sized_strscpy_pad(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src))
458a3bf82df4fe Tobin C. Harding 2019-04-05   90  
e6584c3964f2ff Kees Cook        2023-09-20   91  /**
e6584c3964f2ff Kees Cook        2023-09-20   92   * strscpy - Copy a C-string into a sized buffer
e6584c3964f2ff Kees Cook        2023-09-20   93   * @dst: Where to copy the string to
e6584c3964f2ff Kees Cook        2023-09-20   94   * @src: Where to copy the string from
e6584c3964f2ff Kees Cook        2023-09-20   95   * @...: Size of destination buffer (optional)
e6584c3964f2ff Kees Cook        2023-09-20   96   *
e6584c3964f2ff Kees Cook        2023-09-20   97   * Copy the source string @src, or as much of it as fits, into the
e6584c3964f2ff Kees Cook        2023-09-20   98   * destination @dst buffer. The behavior is undefined if the string
e6584c3964f2ff Kees Cook        2023-09-20   99   * buffers overlap. The destination @dst buffer is always NUL terminated,
e6584c3964f2ff Kees Cook        2023-09-20  100   * unless it's zero-sized.
e6584c3964f2ff Kees Cook        2023-09-20  101   *
e6584c3964f2ff Kees Cook        2023-09-20  102   * The size argument @... is only required when @dst is not an array, or
e6584c3964f2ff Kees Cook        2023-09-20  103   * when the copy needs to be smaller than sizeof(@dst).
e6584c3964f2ff Kees Cook        2023-09-20  104   *
e6584c3964f2ff Kees Cook        2023-09-20  105   * Preferred to strncpy() since it always returns a valid string, and
e6584c3964f2ff Kees Cook        2023-09-20  106   * doesn't unnecessarily force the tail of the destination buffer to be
e6584c3964f2ff Kees Cook        2023-09-20  107   * zero padded. If padding is desired please use strscpy_pad().
e6584c3964f2ff Kees Cook        2023-09-20  108   *
e6584c3964f2ff Kees Cook        2023-09-20  109   * Returns the number of characters copied in @dst (not including the
e6584c3964f2ff Kees Cook        2023-09-20  110   * trailing %NUL) or -E2BIG if @size is 0 or the copy from @src was
e6584c3964f2ff Kees Cook        2023-09-20  111   * truncated.
e6584c3964f2ff Kees Cook        2023-09-20  112   */
e6584c3964f2ff Kees Cook        2023-09-20  113  #define strscpy(dst, src, ...)	\
e6584c3964f2ff Kees Cook        2023-09-20  114  	CONCATENATE(__strscpy, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
458a3bf82df4fe Tobin C. Harding 2019-04-05  115  
8366d124ec937c Kees Cook        2024-02-02 @116  #define sized_strscpy_pad(dest, src, count)	({			\
8366d124ec937c Kees Cook        2024-02-02  117  	char *__dst = (dest);						\
8366d124ec937c Kees Cook        2024-02-02  118  	const char *__src = (src);					\
8366d124ec937c Kees Cook        2024-02-02  119  	const size_t __count = (count);					\
8366d124ec937c Kees Cook        2024-02-02  120  	ssize_t __wrote;						\
8366d124ec937c Kees Cook        2024-02-02  121  									\
8366d124ec937c Kees Cook        2024-02-02  122  	__wrote = sized_strscpy(__dst, __src, __count);			\
8366d124ec937c Kees Cook        2024-02-02  123  	if (__wrote >= 0 && __wrote < __count)				\
8366d124ec937c Kees Cook        2024-02-02  124  		memset(__dst + __wrote + 1, 0, __count - __wrote - 1);	\
8366d124ec937c Kees Cook        2024-02-02  125  	__wrote;							\
8366d124ec937c Kees Cook        2024-02-02  126  })
8366d124ec937c Kees Cook        2024-02-02  127  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'

[Bhupesh Sharma]

Hi,

On 8/11/25 4:55 PM, kernel test robot wrote:
> Hi Bhupesh,
>
> kernel test robot noticed the following build errors:
>
> [auto build test ERROR on next-20250808]
> [cannot apply to trace/for-next tip/sched/core brauner-vfs/vfs.all linus/master v6.17-rc1 v6.16 v6.16-rc7 v6.17-rc1]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url:    https://github.com/intel-lab-lkp/linux/commits/Bhupesh/exec-Remove-obsolete-comments/20250811-144920
> base:   next-20250808
> patch link:    https://lore.kernel.org/r/20250811064609.918593-4-bhupesh%40igalia.com
> patch subject: [PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'
> config: sh-randconfig-002-20250811 (https://download.01.org/0day-ci/archive/20250811/202508111835.JFL8DgKY-lkp@intel.com/config)
> compiler: sh4-linux-gcc (GCC) 15.1.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250811/202508111835.JFL8DgKY-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202508111835.JFL8DgKY-lkp@intel.com/
>
> All errors (new ones prefixed by >>):
>
>     In file included from include/linux/bitmap.h:13,
>                      from include/linux/cpumask.h:12,
>                      from include/linux/smp.h:13,
>                      from include/linux/lockdep.h:14,
>                      from include/linux/spinlock.h:63,
>                      from include/linux/mmzone.h:8,
>                      from include/linux/gfp.h:7,
>                      from include/linux/umh.h:4,
>                      from include/linux/kmod.h:9,
>                      from include/linux/module.h:18,
>                      from net/netfilter/nf_tables_api.c:8:
>     net/netfilter/nf_tables_api.c: In function 'nf_tables_fill_gen_info':
>>> include/linux/string.h:116:50: error: passing argument 3 of 'nla_put_string' makes pointer from integer without a cast [-Wint-conversion]
>       116 | #define sized_strscpy_pad(dest, src, count)     ({                      \
>           |                                                 ~^~~~~~~~~~~~~~~~~~~~~~~~
>           |                                                  |
>           |                                                  ssize_t {aka int}
>       117 |         char *__dst = (dest);                                           \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       118 |         const char *__src = (src);                                      \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       119 |         const size_t __count = (count);                                 \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       120 |         ssize_t __wrote;                                                \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       121 |                                                                         \
>           |                                                                         ~
>       122 |         __wrote = sized_strscpy(__dst, __src, __count);                 \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       123 |         if (__wrote >= 0 && __wrote < __count)                          \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       124 |                 memset(__dst + __wrote + 1, 0, __count - __wrote - 1);  \
>           |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       125 |         __wrote;                                                        \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       126 | })
>           | ~~
>     include/linux/string.h:86:9: note: in expansion of macro 'sized_strscpy_pad'
>        86 |         sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) +        \
>           |         ^~~~~~~~~~~~~~~~~
>     include/linux/args.h:25:24: note: in expansion of macro '__strscpy_pad0'
>        25 | #define __CONCAT(a, b) a ## b
>           |                        ^
>     include/linux/args.h:26:27: note: in expansion of macro '__CONCAT'
>        26 | #define CONCATENATE(a, b) __CONCAT(a, b)
>           |                           ^~~~~~~~
>     include/linux/string.h:149:9: note: in expansion of macro 'CONCATENATE'
>       149 |         CONCATENATE(__strscpy_pad, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
>           |         ^~~~~~~~~~~
>     net/netfilter/nf_tables_api.c:9661:53: note: in expansion of macro 'strscpy_pad'
>      9661 |             nla_put_string(skb, NFTA_GEN_PROC_NAME, strscpy_pad(buf, current->comm)))
>           |                                                     ^~~~~~~~~~~
>     In file included from include/linux/netfilter/nfnetlink.h:7,
>                      from net/netfilter/nf_tables_api.c:17:
>     include/net/netlink.h:1655:46: note: expected 'const char *' but argument is of type 'ssize_t' {aka 'int'}
>      1655 |                                  const char *str)
>           |                                  ~~~~~~~~~~~~^~~
>
>
> vim +/nla_put_string +116 include/linux/string.h
>
> e6584c3964f2ff Kees Cook        2023-09-20   74
> e6584c3964f2ff Kees Cook        2023-09-20   75  /*
> e6584c3964f2ff Kees Cook        2023-09-20   76   * The 2 argument style can only be used when dst is an array with a
> e6584c3964f2ff Kees Cook        2023-09-20   77   * known size.
> e6584c3964f2ff Kees Cook        2023-09-20   78   */
> e6584c3964f2ff Kees Cook        2023-09-20   79  #define __strscpy0(dst, src, ...)	\
> 559048d156ff33 Kees Cook        2024-08-05   80  	sized_strscpy(dst, src, sizeof(dst) + __must_be_array(dst) +	\
> 559048d156ff33 Kees Cook        2024-08-05   81  				__must_be_cstr(dst) + __must_be_cstr(src))
> 559048d156ff33 Kees Cook        2024-08-05   82  #define __strscpy1(dst, src, size)	\
> 559048d156ff33 Kees Cook        2024-08-05   83  	sized_strscpy(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src))
> e6584c3964f2ff Kees Cook        2023-09-20   84
> 8366d124ec937c Kees Cook        2024-02-02   85  #define __strscpy_pad0(dst, src, ...)	\
> 559048d156ff33 Kees Cook        2024-08-05   86  	sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) +	\
> 559048d156ff33 Kees Cook        2024-08-05   87  				    __must_be_cstr(dst) + __must_be_cstr(src))
> 559048d156ff33 Kees Cook        2024-08-05   88  #define __strscpy_pad1(dst, src, size)	\
> 559048d156ff33 Kees Cook        2024-08-05   89  	sized_strscpy_pad(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src))
> 458a3bf82df4fe Tobin C. Harding 2019-04-05   90
> e6584c3964f2ff Kees Cook        2023-09-20   91  /**
> e6584c3964f2ff Kees Cook        2023-09-20   92   * strscpy - Copy a C-string into a sized buffer
> e6584c3964f2ff Kees Cook        2023-09-20   93   * @dst: Where to copy the string to
> e6584c3964f2ff Kees Cook        2023-09-20   94   * @src: Where to copy the string from
> e6584c3964f2ff Kees Cook        2023-09-20   95   * @...: Size of destination buffer (optional)
> e6584c3964f2ff Kees Cook        2023-09-20   96   *
> e6584c3964f2ff Kees Cook        2023-09-20   97   * Copy the source string @src, or as much of it as fits, into the
> e6584c3964f2ff Kees Cook        2023-09-20   98   * destination @dst buffer. The behavior is undefined if the string
> e6584c3964f2ff Kees Cook        2023-09-20   99   * buffers overlap. The destination @dst buffer is always NUL terminated,
> e6584c3964f2ff Kees Cook        2023-09-20  100   * unless it's zero-sized.
> e6584c3964f2ff Kees Cook        2023-09-20  101   *
> e6584c3964f2ff Kees Cook        2023-09-20  102   * The size argument @... is only required when @dst is not an array, or
> e6584c3964f2ff Kees Cook        2023-09-20  103   * when the copy needs to be smaller than sizeof(@dst).
> e6584c3964f2ff Kees Cook        2023-09-20  104   *
> e6584c3964f2ff Kees Cook        2023-09-20  105   * Preferred to strncpy() since it always returns a valid string, and
> e6584c3964f2ff Kees Cook        2023-09-20  106   * doesn't unnecessarily force the tail of the destination buffer to be
> e6584c3964f2ff Kees Cook        2023-09-20  107   * zero padded. If padding is desired please use strscpy_pad().
> e6584c3964f2ff Kees Cook        2023-09-20  108   *
> e6584c3964f2ff Kees Cook        2023-09-20  109   * Returns the number of characters copied in @dst (not including the
> e6584c3964f2ff Kees Cook        2023-09-20  110   * trailing %NUL) or -E2BIG if @size is 0 or the copy from @src was
> e6584c3964f2ff Kees Cook        2023-09-20  111   * truncated.
> e6584c3964f2ff Kees Cook        2023-09-20  112   */
> e6584c3964f2ff Kees Cook        2023-09-20  113  #define strscpy(dst, src, ...)	\
> e6584c3964f2ff Kees Cook        2023-09-20  114  	CONCATENATE(__strscpy, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
> 458a3bf82df4fe Tobin C. Harding 2019-04-05  115
> 8366d124ec937c Kees Cook        2024-02-02 @116  #define sized_strscpy_pad(dest, src, count)	({			\
> 8366d124ec937c Kees Cook        2024-02-02  117  	char *__dst = (dest);						\
> 8366d124ec937c Kees Cook        2024-02-02  118  	const char *__src = (src);					\
> 8366d124ec937c Kees Cook        2024-02-02  119  	const size_t __count = (count);					\
> 8366d124ec937c Kees Cook        2024-02-02  120  	ssize_t __wrote;						\
> 8366d124ec937c Kees Cook        2024-02-02  121  									\
> 8366d124ec937c Kees Cook        2024-02-02  122  	__wrote = sized_strscpy(__dst, __src, __count);			\
> 8366d124ec937c Kees Cook        2024-02-02  123  	if (__wrote >= 0 && __wrote < __count)				\
> 8366d124ec937c Kees Cook        2024-02-02  124  		memset(__dst + __wrote + 1, 0, __count - __wrote - 1);	\
> 8366d124ec937c Kees Cook        2024-02-02  125  	__wrote;							\
> 8366d124ec937c Kees Cook        2024-02-02  126  })
> 8366d124ec937c Kees Cook        2024-02-02  127
>

As mentioned in the accompanying cover letter, this patchset is based on 
'linux-next/master' (the exact sha-id used for rebase is: 
b1549501188cc9eba732c25b033df7a53ccc341f ).

Thanks,
Bhupesh

Re: [PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'

[Andy Shevchenko]

On Mon, Aug 11, 2025 at 08:19:08PM +0530, Bhupesh Sharma wrote:
> On 8/11/25 4:55 PM, kernel test robot wrote:

> As mentioned in the accompanying cover letter, this patchset is based on
> 'linux-next/master' (the exact sha-id used for rebase is:
> b1549501188cc9eba732c25b033df7a53ccc341f ).

Instead of getting false positive reports and this rather unneeded reply from
you, use --base parameter when formatting patch series. It will help all,
including CIs and bots.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'

[Bhupesh Sharma]

On 8/11/25 8:28 PM, Andy Shevchenko wrote:
> On Mon, Aug 11, 2025 at 08:19:08PM +0530, Bhupesh Sharma wrote:
>> On 8/11/25 4:55 PM, kernel test robot wrote:
>> As mentioned in the accompanying cover letter, this patchset is based on
>> 'linux-next/master' (the exact sha-id used for rebase is:
>> b1549501188cc9eba732c25b033df7a53ccc341f ).
> Instead of getting false positive reports and this rather unneeded reply from
> you, use --base parameter when formatting patch series. It will help all,
> including CIs and bots.
>

Sure, will include it in next version. Waiting for further reviews on 
this v7.

Thanks.

Re: [PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'

[Andy Shevchenko]

On Mon, Aug 11, 2025 at 12:16:08PM +0530, Bhupesh wrote:
> As Linus mentioned in [1], we should get rid of 'get_task_comm()'
> entirely and replace it with 'strscpy_pad()' implementation.
> 
> 'strscpy_pad()' will already make sure comm is NUL-terminated, so
> we won't need the explicit final byte termination done in
> 'get_task_comm()'.
> 
> The relevant 'get_task_comm()' users were identified using the
> following search pattern:
>  $ git grep 'get_task_comm*'

> [1]. https://lore.kernel.org/all/CAHk-=wi5c=_-FBGo_88CowJd_F-Gi6Ud9d=TALm65ReN7YjrMw@mail.gmail.com/
> 
> Signed-off-by: Bhupesh <bhupesh@igalia.com>

Make that a Link tag?

  Link: https://lore.kernel.org/all/CAHk-=wi5c=_-FBGo_88CowJd_F-Gi6Ud9d=TALm65ReN7YjrMw@mail.gmail.com/ #1
  Signed-off-by: Bhupesh <bhupesh@igalia.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'

[Bhupesh Sharma]

On 8/11/25 8:35 PM, Andy Shevchenko wrote:
> On Mon, Aug 11, 2025 at 12:16:08PM +0530, Bhupesh wrote:
>> As Linus mentioned in [1], we should get rid of 'get_task_comm()'
>> entirely and replace it with 'strscpy_pad()' implementation.
>>
>> 'strscpy_pad()' will already make sure comm is NUL-terminated, so
>> we won't need the explicit final byte termination done in
>> 'get_task_comm()'.
>>
>> The relevant 'get_task_comm()' users were identified using the
>> following search pattern:
>>   $ git grep 'get_task_comm*'
>> [1]. https://lore.kernel.org/all/CAHk-=wi5c=_-FBGo_88CowJd_F-Gi6Ud9d=TALm65ReN7YjrMw@mail.gmail.com/
>>
>> Signed-off-by: Bhupesh <bhupesh@igalia.com>
> Make that a Link tag?
>
>    Link: https://lore.kernel.org/all/CAHk-=wi5c=_-FBGo_88CowJd_F-Gi6Ud9d=TALm65ReN7YjrMw@mail.gmail.com/ #1
>    Signed-off-by: Bhupesh <bhupesh@igalia.com>
>

Sure, will include it in next version. Waiting for further reviews on 
this v7.

Thanks.

Re: [PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'

[kernel test robot]

Hi Bhupesh,

kernel test robot noticed the following build warnings:

[auto build test WARNING on next-20250808]
[cannot apply to trace/for-next tip/sched/core brauner-vfs/vfs.all linus/master v6.17-rc1 v6.16 v6.16-rc7 v6.17-rc1]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Bhupesh/exec-Remove-obsolete-comments/20250811-144920
base:   next-20250808
patch link:    https://lore.kernel.org/r/20250811064609.918593-4-bhupesh%40igalia.com
patch subject: [PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'
config: arc-randconfig-002-20250812 (https://download.01.org/0day-ci/archive/20250812/202508121145.d07aFegg-lkp@intel.com/config)
compiler: arc-linux-gcc (GCC) 12.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250812/202508121145.d07aFegg-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202508121145.d07aFegg-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/linux/build_bug.h:5,
                    from include/linux/container_of.h:5,
                    from include/linux/list.h:5,
                    from include/linux/module.h:12,
                    from net/netfilter/nf_tables_api.c:8:
   net/netfilter/nf_tables_api.c: In function 'nf_tables_fill_gen_info':
>> include/linux/string.h:116:50: warning: passing argument 3 of 'nla_put_string' makes pointer from integer without a cast [-Wint-conversion]
     116 | #define sized_strscpy_pad(dest, src, count)     ({                      \
         |                                                 ~^~~~~~~~~~~~~~~~~~~~~~~~
         |                                                  |
         |                                                  ssize_t {aka int}
     117 |         char *__dst = (dest);                                           \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     118 |         const char *__src = (src);                                      \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     119 |         const size_t __count = (count);                                 \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     120 |         ssize_t __wrote;                                                \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     121 |                                                                         \
         |                                                                         ~
     122 |         __wrote = sized_strscpy(__dst, __src, __count);                 \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     123 |         if (__wrote >= 0 && __wrote < __count)                          \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     124 |                 memset(__dst + __wrote + 1, 0, __count - __wrote - 1);  \
         |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     125 |         __wrote;                                                        \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     126 | })
         | ~~                                                
   include/linux/compiler.h:57:52: note: in definition of macro '__trace_if_var'
      57 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
         |                                                    ^~~~
   net/netfilter/nf_tables_api.c:9659:9: note: in expansion of macro 'if'
    9659 |         if (nla_put_be32(skb, NFTA_GEN_ID, htonl(nft_net->base_seq)) ||
         |         ^~
   include/linux/string.h:86:9: note: in expansion of macro 'sized_strscpy_pad'
      86 |         sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) +        \
         |         ^~~~~~~~~~~~~~~~~
   include/linux/args.h:25:24: note: in expansion of macro '__strscpy_pad0'
      25 | #define __CONCAT(a, b) a ## b
         |                        ^
   include/linux/args.h:26:27: note: in expansion of macro '__CONCAT'
      26 | #define CONCATENATE(a, b) __CONCAT(a, b)
         |                           ^~~~~~~~
   include/linux/string.h:149:9: note: in expansion of macro 'CONCATENATE'
     149 |         CONCATENATE(__strscpy_pad, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
         |         ^~~~~~~~~~~
   net/netfilter/nf_tables_api.c:9661:53: note: in expansion of macro 'strscpy_pad'
    9661 |             nla_put_string(skb, NFTA_GEN_PROC_NAME, strscpy_pad(buf, current->comm)))
         |                                                     ^~~~~~~~~~~
   In file included from include/linux/netfilter/nfnetlink.h:7,
                    from net/netfilter/nf_tables_api.c:17:
   include/net/netlink.h:1655:46: note: expected 'const char *' but argument is of type 'ssize_t' {aka 'int'}
    1655 |                                  const char *str)
         |                                  ~~~~~~~~~~~~^~~
>> include/linux/string.h:116:50: warning: passing argument 3 of 'nla_put_string' makes pointer from integer without a cast [-Wint-conversion]
     116 | #define sized_strscpy_pad(dest, src, count)     ({                      \
         |                                                 ~^~~~~~~~~~~~~~~~~~~~~~~~
         |                                                  |
         |                                                  ssize_t {aka int}
     117 |         char *__dst = (dest);                                           \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     118 |         const char *__src = (src);                                      \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     119 |         const size_t __count = (count);                                 \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     120 |         ssize_t __wrote;                                                \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     121 |                                                                         \
         |                                                                         ~
     122 |         __wrote = sized_strscpy(__dst, __src, __count);                 \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     123 |         if (__wrote >= 0 && __wrote < __count)                          \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     124 |                 memset(__dst + __wrote + 1, 0, __count - __wrote - 1);  \
         |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     125 |         __wrote;                                                        \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     126 | })
         | ~~                                                
   include/linux/compiler.h:57:61: note: in definition of macro '__trace_if_var'
      57 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
         |                                                             ^~~~
   net/netfilter/nf_tables_api.c:9659:9: note: in expansion of macro 'if'
    9659 |         if (nla_put_be32(skb, NFTA_GEN_ID, htonl(nft_net->base_seq)) ||
         |         ^~
   include/linux/string.h:86:9: note: in expansion of macro 'sized_strscpy_pad'
      86 |         sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) +        \
         |         ^~~~~~~~~~~~~~~~~
   include/linux/args.h:25:24: note: in expansion of macro '__strscpy_pad0'
      25 | #define __CONCAT(a, b) a ## b
         |                        ^
   include/linux/args.h:26:27: note: in expansion of macro '__CONCAT'
      26 | #define CONCATENATE(a, b) __CONCAT(a, b)
         |                           ^~~~~~~~
   include/linux/string.h:149:9: note: in expansion of macro 'CONCATENATE'
     149 |         CONCATENATE(__strscpy_pad, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
         |         ^~~~~~~~~~~
   net/netfilter/nf_tables_api.c:9661:53: note: in expansion of macro 'strscpy_pad'
    9661 |             nla_put_string(skb, NFTA_GEN_PROC_NAME, strscpy_pad(buf, current->comm)))
         |                                                     ^~~~~~~~~~~
   include/net/netlink.h:1655:46: note: expected 'const char *' but argument is of type 'ssize_t' {aka 'int'}
    1655 |                                  const char *str)
         |                                  ~~~~~~~~~~~~^~~
>> include/linux/string.h:116:50: warning: passing argument 3 of 'nla_put_string' makes pointer from integer without a cast [-Wint-conversion]
     116 | #define sized_strscpy_pad(dest, src, count)     ({                      \
         |                                                 ~^~~~~~~~~~~~~~~~~~~~~~~~
         |                                                  |
         |                                                  ssize_t {aka int}
     117 |         char *__dst = (dest);                                           \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     118 |         const char *__src = (src);                                      \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     119 |         const size_t __count = (count);                                 \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     120 |         ssize_t __wrote;                                                \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     121 |                                                                         \
         |                                                                         ~
     122 |         __wrote = sized_strscpy(__dst, __src, __count);                 \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     123 |         if (__wrote >= 0 && __wrote < __count)                          \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     124 |                 memset(__dst + __wrote + 1, 0, __count - __wrote - 1);  \
         |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     125 |         __wrote;                                                        \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     126 | })
         | ~~                                                
   include/linux/compiler.h:68:10: note: in definition of macro '__trace_if_value'
      68 |         (cond) ?                                        \
         |          ^~~~
   include/linux/compiler.h:55:28: note: in expansion of macro '__trace_if_var'
      55 | #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
         |                            ^~~~~~~~~~~~~~
   net/netfilter/nf_tables_api.c:9659:9: note: in expansion of macro 'if'
    9659 |         if (nla_put_be32(skb, NFTA_GEN_ID, htonl(nft_net->base_seq)) ||
         |         ^~
   include/linux/string.h:86:9: note: in expansion of macro 'sized_strscpy_pad'
      86 |         sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) +        \
         |         ^~~~~~~~~~~~~~~~~
   include/linux/args.h:25:24: note: in expansion of macro '__strscpy_pad0'
      25 | #define __CONCAT(a, b) a ## b
         |                        ^
   include/linux/args.h:26:27: note: in expansion of macro '__CONCAT'
      26 | #define CONCATENATE(a, b) __CONCAT(a, b)
         |                           ^~~~~~~~
   include/linux/string.h:149:9: note: in expansion of macro 'CONCATENATE'
     149 |         CONCATENATE(__strscpy_pad, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
         |         ^~~~~~~~~~~
   net/netfilter/nf_tables_api.c:9661:53: note: in expansion of macro 'strscpy_pad'
    9661 |             nla_put_string(skb, NFTA_GEN_PROC_NAME, strscpy_pad(buf, current->comm)))
         |                                                     ^~~~~~~~~~~
   include/net/netlink.h:1655:46: note: expected 'const char *' but argument is of type 'ssize_t' {aka 'int'}
    1655 |                                  const char *str)
         |                                  ~~~~~~~~~~~~^~~


vim +/nla_put_string +116 include/linux/string.h

e6584c3964f2ff Kees Cook        2023-09-20   74  
e6584c3964f2ff Kees Cook        2023-09-20   75  /*
e6584c3964f2ff Kees Cook        2023-09-20   76   * The 2 argument style can only be used when dst is an array with a
e6584c3964f2ff Kees Cook        2023-09-20   77   * known size.
e6584c3964f2ff Kees Cook        2023-09-20   78   */
e6584c3964f2ff Kees Cook        2023-09-20   79  #define __strscpy0(dst, src, ...)	\
559048d156ff33 Kees Cook        2024-08-05   80  	sized_strscpy(dst, src, sizeof(dst) + __must_be_array(dst) +	\
559048d156ff33 Kees Cook        2024-08-05   81  				__must_be_cstr(dst) + __must_be_cstr(src))
559048d156ff33 Kees Cook        2024-08-05   82  #define __strscpy1(dst, src, size)	\
559048d156ff33 Kees Cook        2024-08-05   83  	sized_strscpy(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src))
e6584c3964f2ff Kees Cook        2023-09-20   84  
8366d124ec937c Kees Cook        2024-02-02   85  #define __strscpy_pad0(dst, src, ...)	\
559048d156ff33 Kees Cook        2024-08-05   86  	sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) +	\
559048d156ff33 Kees Cook        2024-08-05   87  				    __must_be_cstr(dst) + __must_be_cstr(src))
559048d156ff33 Kees Cook        2024-08-05   88  #define __strscpy_pad1(dst, src, size)	\
559048d156ff33 Kees Cook        2024-08-05   89  	sized_strscpy_pad(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src))
458a3bf82df4fe Tobin C. Harding 2019-04-05   90  
e6584c3964f2ff Kees Cook        2023-09-20   91  /**
e6584c3964f2ff Kees Cook        2023-09-20   92   * strscpy - Copy a C-string into a sized buffer
e6584c3964f2ff Kees Cook        2023-09-20   93   * @dst: Where to copy the string to
e6584c3964f2ff Kees Cook        2023-09-20   94   * @src: Where to copy the string from
e6584c3964f2ff Kees Cook        2023-09-20   95   * @...: Size of destination buffer (optional)
e6584c3964f2ff Kees Cook        2023-09-20   96   *
e6584c3964f2ff Kees Cook        2023-09-20   97   * Copy the source string @src, or as much of it as fits, into the
e6584c3964f2ff Kees Cook        2023-09-20   98   * destination @dst buffer. The behavior is undefined if the string
e6584c3964f2ff Kees Cook        2023-09-20   99   * buffers overlap. The destination @dst buffer is always NUL terminated,
e6584c3964f2ff Kees Cook        2023-09-20  100   * unless it's zero-sized.
e6584c3964f2ff Kees Cook        2023-09-20  101   *
e6584c3964f2ff Kees Cook        2023-09-20  102   * The size argument @... is only required when @dst is not an array, or
e6584c3964f2ff Kees Cook        2023-09-20  103   * when the copy needs to be smaller than sizeof(@dst).
e6584c3964f2ff Kees Cook        2023-09-20  104   *
e6584c3964f2ff Kees Cook        2023-09-20  105   * Preferred to strncpy() since it always returns a valid string, and
e6584c3964f2ff Kees Cook        2023-09-20  106   * doesn't unnecessarily force the tail of the destination buffer to be
e6584c3964f2ff Kees Cook        2023-09-20  107   * zero padded. If padding is desired please use strscpy_pad().
e6584c3964f2ff Kees Cook        2023-09-20  108   *
e6584c3964f2ff Kees Cook        2023-09-20  109   * Returns the number of characters copied in @dst (not including the
e6584c3964f2ff Kees Cook        2023-09-20  110   * trailing %NUL) or -E2BIG if @size is 0 or the copy from @src was
e6584c3964f2ff Kees Cook        2023-09-20  111   * truncated.
e6584c3964f2ff Kees Cook        2023-09-20  112   */
e6584c3964f2ff Kees Cook        2023-09-20  113  #define strscpy(dst, src, ...)	\
e6584c3964f2ff Kees Cook        2023-09-20  114  	CONCATENATE(__strscpy, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
458a3bf82df4fe Tobin C. Harding 2019-04-05  115  
8366d124ec937c Kees Cook        2024-02-02 @116  #define sized_strscpy_pad(dest, src, count)	({			\
8366d124ec937c Kees Cook        2024-02-02  117  	char *__dst = (dest);						\
8366d124ec937c Kees Cook        2024-02-02  118  	const char *__src = (src);					\
8366d124ec937c Kees Cook        2024-02-02  119  	const size_t __count = (count);					\
8366d124ec937c Kees Cook        2024-02-02  120  	ssize_t __wrote;						\
8366d124ec937c Kees Cook        2024-02-02  121  									\
8366d124ec937c Kees Cook        2024-02-02  122  	__wrote = sized_strscpy(__dst, __src, __count);			\
8366d124ec937c Kees Cook        2024-02-02  123  	if (__wrote >= 0 && __wrote < __count)				\
8366d124ec937c Kees Cook        2024-02-02  124  		memset(__dst + __wrote + 1, 0, __count - __wrote - 1);	\
8366d124ec937c Kees Cook        2024-02-02  125  	__wrote;							\
8366d124ec937c Kees Cook        2024-02-02  126  })
8366d124ec937c Kees Cook        2024-02-02  127  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

[PATCH v7 4/4] treewide: Switch memcpy() users of 'task->comm' to a more safer implementation

[Bhupesh]

As Linus mentioned in [1], currently we have several memcpy() use-cases
which use 'current->comm' to copy the task name over to local copies.
For an example:

 ...
 char comm[TASK_COMM_LEN];
 memcpy(comm, current->comm, TASK_COMM_LEN);
 ...

These should be rather calling a wrappper like "get_task_array()",
which is implemented as:

   static __always_inline void
       __cstr_array_copy(char *dst,
            const char *src, __kernel_size_t size)
   {
        memcpy(dst, src, size);
        dst[size] = 0;
   }

   #define get_task_array(dst,src) \
      __cstr_array_copy(dst, src, __must_be_array(dst))

The relevant 'memcpy()' users were identified using the following search
pattern:
 $ git grep 'memcpy.*->comm\>'

[1]. https://lore.kernel.org/all/CAHk-=wi5c=_-FBGo_88CowJd_F-Gi6Ud9d=TALm65ReN7YjrMw@mail.gmail.com/

Signed-off-by: Bhupesh <bhupesh@igalia.com>
---
 include/linux/coredump.h                      |  2 +-
 include/linux/sched.h                         | 32 +++++++++++++++++++
 include/linux/tracepoint.h                    |  4 +--
 include/trace/events/block.h                  | 10 +++---
 include/trace/events/oom.h                    |  2 +-
 include/trace/events/osnoise.h                |  2 +-
 include/trace/events/sched.h                  | 13 ++++----
 include/trace/events/signal.h                 |  2 +-
 include/trace/events/task.h                   |  4 +--
 tools/bpf/bpftool/pids.c                      |  6 ++--
 .../bpf/test_kmods/bpf_testmod-events.h       |  2 +-
 11 files changed, 54 insertions(+), 25 deletions(-)

diff --git a/include/linux/coredump.h b/include/linux/coredump.h
index 68861da4cf7c..bcee0afc5eaf 100644
--- a/include/linux/coredump.h
+++ b/include/linux/coredump.h
@@ -54,7 +54,7 @@ extern void vfs_coredump(const kernel_siginfo_t *siginfo);
 	do {	\
 		char comm[TASK_COMM_LEN];	\
 		/* This will always be NUL terminated. */ \
-		memcpy(comm, current->comm, sizeof(comm)); \
+		get_task_array(comm, current->comm); \
 		printk_ratelimited(Level "coredump: %d(%*pE): " Format "\n",	\
 			task_tgid_vnr(current), (int)strlen(comm), comm, ##__VA_ARGS__);	\
 	} while (0)	\
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 97ea2ac2a97a..6602ec132297 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1960,12 +1960,44 @@ extern void wake_up_new_task(struct task_struct *tsk);
 
 extern void kick_process(struct task_struct *tsk);
 
+/*
+ * - Why not use task_lock()?
+ *   User space can randomly change their names anyway, so locking for readers
+ *   doesn't make sense. For writers, locking is probably necessary, as a race
+ *   condition could lead to long-term mixed results.
+ *   The logic inside __set_task_comm() should ensure that the task comm is
+ *   always NUL-terminated and zero-padded. Therefore the race condition between
+ *   reader and writer is not an issue.
+ */
+
 extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec);
 #define set_task_comm(tsk, from) ({			\
 	BUILD_BUG_ON(sizeof(from) < TASK_COMM_LEN);	\
 	__set_task_comm(tsk, from, false);		\
 })
 
+/*
+ * 'get_task_array' can be 'data-racy' in the destination and
+ * should not be used for cases where a 'stable NUL at the end'
+ * is needed. Its better to use strscpy and friends for such
+ * use-cases.
+ *
+ * It is suited mainly for a 'just copy comm to a constant-sized
+ * array' case - especially in performance sensitive use-cases,
+ * like tracing.
+ */
+
+static __always_inline void
+	__cstr_array_copy(char *dst, const char *src,
+			  __kernel_size_t size)
+{
+	memcpy(dst, src, size);
+	dst[size] = 0;
+}
+
+#define get_task_array(dst, src) \
+	__cstr_array_copy(dst, src, __must_be_array(dst))
+
 static __always_inline void scheduler_ipi(void)
 {
 	/*
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 826ce3f8e1f8..40e04cb660ce 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -570,10 +570,10 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
  *	*
  *
  *	TP_fast_assign(
- *		memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
+ *		get_task_array(__entry->next_comm, next->comm);
  *		__entry->prev_pid	= prev->pid;
  *		__entry->prev_prio	= prev->prio;
- *		memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
+ *		get_task_array(__entry->prev_comm, prev->comm);
  *		__entry->next_pid	= next->pid;
  *		__entry->next_prio	= next->prio;
  *	),
diff --git a/include/trace/events/block.h b/include/trace/events/block.h
index 6aa79e2d799c..de1fe35333fc 100644
--- a/include/trace/events/block.h
+++ b/include/trace/events/block.h
@@ -213,7 +213,7 @@ DECLARE_EVENT_CLASS(block_rq,
 
 		blk_fill_rwbs(__entry->rwbs, rq->cmd_flags);
 		__get_str(cmd)[0] = '\0';
-		memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, current->comm);
 	),
 
 	TP_printk("%d,%d %s %u (%s) %llu + %u %s,%u,%u [%s]",
@@ -351,7 +351,7 @@ DECLARE_EVENT_CLASS(block_bio,
 		__entry->sector		= bio->bi_iter.bi_sector;
 		__entry->nr_sector	= bio_sectors(bio);
 		blk_fill_rwbs(__entry->rwbs, bio->bi_opf);
-		memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, current->comm);
 	),
 
 	TP_printk("%d,%d %s %llu + %u [%s]",
@@ -434,7 +434,7 @@ TRACE_EVENT(block_plug,
 	),
 
 	TP_fast_assign(
-		memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, current->comm);
 	),
 
 	TP_printk("[%s]", __entry->comm)
@@ -453,7 +453,7 @@ DECLARE_EVENT_CLASS(block_unplug,
 
 	TP_fast_assign(
 		__entry->nr_rq = depth;
-		memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, current->comm);
 	),
 
 	TP_printk("[%s] %d", __entry->comm, __entry->nr_rq)
@@ -504,7 +504,7 @@ TRACE_EVENT(block_split,
 		__entry->sector		= bio->bi_iter.bi_sector;
 		__entry->new_sector	= new_sector;
 		blk_fill_rwbs(__entry->rwbs, bio->bi_opf);
-		memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, current->comm);
 	),
 
 	TP_printk("%d,%d %s %llu / %llu [%s]",
diff --git a/include/trace/events/oom.h b/include/trace/events/oom.h
index 9f0a5d1482c4..31e5b7295188 100644
--- a/include/trace/events/oom.h
+++ b/include/trace/events/oom.h
@@ -23,7 +23,7 @@ TRACE_EVENT(oom_score_adj_update,
 
 	TP_fast_assign(
 		__entry->pid = task->pid;
-		memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, task->comm);
 		__entry->oom_score_adj = task->signal->oom_score_adj;
 	),
 
diff --git a/include/trace/events/osnoise.h b/include/trace/events/osnoise.h
index 3f4273623801..f67f8b5eca75 100644
--- a/include/trace/events/osnoise.h
+++ b/include/trace/events/osnoise.h
@@ -116,7 +116,7 @@ TRACE_EVENT(thread_noise,
 	),
 
 	TP_fast_assign(
-		memcpy(__entry->comm, t->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, t->comm);
 		__entry->pid = t->pid;
 		__entry->start = start;
 		__entry->duration = duration;
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 7b2645b50e78..66fe808f2654 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -152,7 +152,7 @@ DECLARE_EVENT_CLASS(sched_wakeup_template,
 	),
 
 	TP_fast_assign(
-		memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, p->comm);
 		__entry->pid		= p->pid;
 		__entry->prio		= p->prio; /* XXX SCHED_DEADLINE */
 		__entry->target_cpu	= task_cpu(p);
@@ -237,11 +237,11 @@ TRACE_EVENT(sched_switch,
 	),
 
 	TP_fast_assign(
-		memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
+		get_task_array(__entry->prev_comm, prev->comm);
 		__entry->prev_pid	= prev->pid;
 		__entry->prev_prio	= prev->prio;
 		__entry->prev_state	= __trace_sched_switch_state(preempt, prev_state, prev);
-		memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
+		get_task_array(__entry->next_comm, next->comm);
 		__entry->next_pid	= next->pid;
 		__entry->next_prio	= next->prio;
 		/* XXX SCHED_DEADLINE */
@@ -346,7 +346,7 @@ TRACE_EVENT(sched_process_exit,
 	),
 
 	TP_fast_assign(
-		memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, p->comm);
 		__entry->pid		= p->pid;
 		__entry->prio		= p->prio; /* XXX SCHED_DEADLINE */
 		__entry->group_dead	= group_dead;
@@ -787,14 +787,13 @@ TRACE_EVENT(sched_skip_cpuset_numa,
 	),
 
 	TP_fast_assign(
-		memcpy(__entry->comm, tsk->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, tsk->comm);
 		__entry->pid		 = task_pid_nr(tsk);
 		__entry->tgid		 = task_tgid_nr(tsk);
 		__entry->ngid		 = task_numa_group_id(tsk);
 		BUILD_BUG_ON(sizeof(nodemask_t) != \
 			     BITS_TO_LONGS(MAX_NUMNODES) * sizeof(long));
-		memcpy(__entry->mem_allowed, mem_allowed_ptr->bits,
-		       sizeof(__entry->mem_allowed));
+		get_task_array(__entry->mem_allowed, mem_allowed_ptr->bits);
 	),
 
 	TP_printk("comm=%s pid=%d tgid=%d ngid=%d mem_nodes_allowed=%*pbl",
diff --git a/include/trace/events/signal.h b/include/trace/events/signal.h
index 1db7e4b07c01..0681dc5ab1de 100644
--- a/include/trace/events/signal.h
+++ b/include/trace/events/signal.h
@@ -67,7 +67,7 @@ TRACE_EVENT(signal_generate,
 	TP_fast_assign(
 		__entry->sig	= sig;
 		TP_STORE_SIGINFO(__entry, info);
-		memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, task->comm);
 		__entry->pid	= task->pid;
 		__entry->group	= group;
 		__entry->result	= result;
diff --git a/include/trace/events/task.h b/include/trace/events/task.h
index af535b053033..9553946943a6 100644
--- a/include/trace/events/task.h
+++ b/include/trace/events/task.h
@@ -21,7 +21,7 @@ TRACE_EVENT(task_newtask,
 
 	TP_fast_assign(
 		__entry->pid = task->pid;
-		memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, task->comm);
 		__entry->clone_flags = clone_flags;
 		__entry->oom_score_adj = task->signal->oom_score_adj;
 	),
@@ -44,7 +44,7 @@ TRACE_EVENT(task_rename,
 	),
 
 	TP_fast_assign(
-		memcpy(entry->oldcomm, task->comm, TASK_COMM_LEN);
+		get_task_array(entry->oldcomm, task->comm);
 		strscpy(entry->newcomm, comm, TASK_COMM_LEN);
 		__entry->oom_score_adj = task->signal->oom_score_adj;
 	),
diff --git a/tools/bpf/bpftool/pids.c b/tools/bpf/bpftool/pids.c
index 23f488cf1740..a5d339cb8ca3 100644
--- a/tools/bpf/bpftool/pids.c
+++ b/tools/bpf/bpftool/pids.c
@@ -53,8 +53,7 @@ static void add_ref(struct hashmap *map, struct pid_iter_entry *e)
 		refs->refs = tmp;
 		ref = &refs->refs[refs->ref_cnt];
 		ref->pid = e->pid;
-		memcpy(ref->comm, e->comm, sizeof(ref->comm));
-		ref->comm[sizeof(ref->comm) - 1] = '\0';
+		get_task_array(ref->comm, e->comm);
 		refs->ref_cnt++;
 
 		return;
@@ -77,8 +76,7 @@ static void add_ref(struct hashmap *map, struct pid_iter_entry *e)
 	}
 	ref = &refs->refs[0];
 	ref->pid = e->pid;
-	memcpy(ref->comm, e->comm, sizeof(ref->comm));
-	ref->comm[sizeof(ref->comm) - 1] = '\0';
+	get_task_array(ref->comm, e->comm);
 	refs->ref_cnt = 1;
 	refs->has_bpf_cookie = e->has_bpf_cookie;
 	refs->bpf_cookie = e->bpf_cookie;
diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod-events.h b/tools/testing/selftests/bpf/test_kmods/bpf_testmod-events.h
index aeef86b3da74..81880748550f 100644
--- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod-events.h
+++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod-events.h
@@ -20,7 +20,7 @@ TRACE_EVENT(bpf_testmod_test_read,
 	),
 	TP_fast_assign(
 		__entry->pid = task->pid;
-		memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
+		get_task_array(__entry->comm, task->comm);
 		__entry->off = ctx->off;
 		__entry->len = ctx->len;
 	),
-- 
2.38.1

Re: [PATCH v7 4/4] treewide: Switch memcpy() users of 'task->comm' to a more safer implementation

[Andy Shevchenko]

On Mon, Aug 11, 2025 at 12:16:09PM +0530, Bhupesh wrote:
> As Linus mentioned in [1], currently we have several memcpy() use-cases
> which use 'current->comm' to copy the task name over to local copies.
> For an example:
> 
>  ...
>  char comm[TASK_COMM_LEN];
>  memcpy(comm, current->comm, TASK_COMM_LEN);
>  ...
> 
> These should be rather calling a wrappper like "get_task_array()",
> which is implemented as:
> 
>    static __always_inline void
>        __cstr_array_copy(char *dst,
>             const char *src, __kernel_size_t size)
>    {
>         memcpy(dst, src, size);
>         dst[size] = 0;
>    }
> 
>    #define get_task_array(dst,src) \
>       __cstr_array_copy(dst, src, __must_be_array(dst))
> 
> The relevant 'memcpy()' users were identified using the following search
> pattern:
>  $ git grep 'memcpy.*->comm\>'

> [1]. https://lore.kernel.org/all/CAHk-=wi5c=_-FBGo_88CowJd_F-Gi6Ud9d=TALm65ReN7YjrMw@mail.gmail.com/
> 
> Signed-off-by: Bhupesh <bhupesh@igalia.com>

Same suggestion, make it a Link tag.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v7 4/4] treewide: Switch memcpy() users of 'task->comm' to a more safer implementation

[kernel test robot]

Hi Bhupesh,

kernel test robot noticed the following build errors:

[auto build test ERROR on next-20250808]
[cannot apply to trace/for-next tip/sched/core brauner-vfs/vfs.all linus/master v6.17-rc1 v6.16 v6.16-rc7 v6.17-rc1]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Bhupesh/exec-Remove-obsolete-comments/20250811-144920
base:   next-20250808
patch link:    https://lore.kernel.org/r/20250811064609.918593-5-bhupesh%40igalia.com
patch subject: [PATCH v7 4/4] treewide: Switch memcpy() users of 'task->comm' to a more safer implementation
config: x86_64-buildonly-randconfig-001-20250811 (https://download.01.org/0day-ci/archive/20250812/202508120011.j4Pmr6Rf-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14+deb12u1) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250812/202508120011.j4Pmr6Rf-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202508120011.j4Pmr6Rf-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from include/trace/define_trace.h:132,
                    from include/trace/events/sched.h:901,
                    from kernel/sched/core.c:85:
   include/trace/events/sched.h: In function 'do_trace_event_raw_event_sched_skip_cpuset_numa':
>> include/trace/events/sched.h:796:39: error: passing argument 1 of '__cstr_array_copy' from incompatible pointer type [-Werror=incompatible-pointer-types]
     796 |                 get_task_array(__entry->mem_allowed, mem_allowed_ptr->bits);
   include/trace/trace_events.h:427:11: note: in definition of macro '__DECLARE_EVENT_CLASS'
     427 |         { assign; }                                                     \
         |           ^~~~~~
   include/trace/trace_events.h:435:23: note: in expansion of macro 'PARAMS'
     435 |                       PARAMS(assign), PARAMS(print))                    \
         |                       ^~~~~~
   include/trace/trace_events.h:40:9: note: in expansion of macro 'DECLARE_EVENT_CLASS'
      40 |         DECLARE_EVENT_CLASS(name,                              \
         |         ^~~~~~~~~~~~~~~~~~~
   include/trace/trace_events.h:44:30: note: in expansion of macro 'PARAMS'
      44 |                              PARAMS(assign),                   \
         |                              ^~~~~~
   include/trace/events/sched.h:775:1: note: in expansion of macro 'TRACE_EVENT'
     775 | TRACE_EVENT(sched_skip_cpuset_numa,
         | ^~~~~~~~~~~
   include/trace/events/sched.h:789:9: note: in expansion of macro 'TP_fast_assign'
     789 |         TP_fast_assign(
         |         ^~~~~~~~~~~~~~
   include/trace/events/sched.h:796:17: note: in expansion of macro 'get_task_array'
     796 |                 get_task_array(__entry->mem_allowed, mem_allowed_ptr->bits);
         |                 ^~~~~~~~~~~~~~
   In file included from include/linux/percpu.h:12,
                    from arch/x86/include/asm/msr.h:16,
                    from arch/x86/include/asm/tsc.h:11,
                    from arch/x86/include/asm/timex.h:6,
                    from include/linux/timex.h:67,
                    from include/linux/time32.h:13,
                    from include/linux/time.h:60,
                    from include/linux/stat.h:19,
                    from include/linux/fs.h:11,
                    from include/linux/highmem.h:5,
                    from kernel/sched/core.c:10:
   include/linux/sched.h:1991:33: note: expected 'char *' but argument is of type 'long unsigned int *'
    1991 |         __cstr_array_copy(char *dst, const char *src,
         |                           ~~~~~~^~~
   include/trace/events/sched.h:796:69: error: passing argument 2 of '__cstr_array_copy' from incompatible pointer type [-Werror=incompatible-pointer-types]
     796 |                 get_task_array(__entry->mem_allowed, mem_allowed_ptr->bits);
         |                                                      ~~~~~~~~~~~~~~~^~~~~~
         |                                                                     |
         |                                                                     long unsigned int *
   include/trace/trace_events.h:427:11: note: in definition of macro '__DECLARE_EVENT_CLASS'
     427 |         { assign; }                                                     \
         |           ^~~~~~
   include/trace/trace_events.h:435:23: note: in expansion of macro 'PARAMS'
     435 |                       PARAMS(assign), PARAMS(print))                    \
         |                       ^~~~~~
   include/trace/trace_events.h:40:9: note: in expansion of macro 'DECLARE_EVENT_CLASS'
      40 |         DECLARE_EVENT_CLASS(name,                              \
         |         ^~~~~~~~~~~~~~~~~~~
   include/trace/trace_events.h:44:30: note: in expansion of macro 'PARAMS'
      44 |                              PARAMS(assign),                   \
         |                              ^~~~~~
   include/trace/events/sched.h:775:1: note: in expansion of macro 'TRACE_EVENT'
     775 | TRACE_EVENT(sched_skip_cpuset_numa,
         | ^~~~~~~~~~~
   include/trace/events/sched.h:789:9: note: in expansion of macro 'TP_fast_assign'
     789 |         TP_fast_assign(
         |         ^~~~~~~~~~~~~~
   include/trace/events/sched.h:796:17: note: in expansion of macro 'get_task_array'
     796 |                 get_task_array(__entry->mem_allowed, mem_allowed_ptr->bits);
         |                 ^~~~~~~~~~~~~~
   include/linux/sched.h:1991:50: note: expected 'const char *' but argument is of type 'long unsigned int *'
    1991 |         __cstr_array_copy(char *dst, const char *src,
         |                                      ~~~~~~~~~~~~^~~
   In file included from include/trace/define_trace.h:133:
   include/trace/events/sched.h: In function 'do_perf_trace_sched_skip_cpuset_numa':
>> include/trace/events/sched.h:796:39: error: passing argument 1 of '__cstr_array_copy' from incompatible pointer type [-Werror=incompatible-pointer-types]
     796 |                 get_task_array(__entry->mem_allowed, mem_allowed_ptr->bits);
   include/trace/perf.h:51:11: note: in definition of macro '__DECLARE_EVENT_CLASS'
      51 |         { assign; }                                                     \
         |           ^~~~~~
   include/trace/perf.h:67:23: note: in expansion of macro 'PARAMS'
      67 |                       PARAMS(assign), PARAMS(print))                    \
         |                       ^~~~~~
   include/trace/trace_events.h:40:9: note: in expansion of macro 'DECLARE_EVENT_CLASS'
      40 |         DECLARE_EVENT_CLASS(name,                              \
         |         ^~~~~~~~~~~~~~~~~~~
   include/trace/trace_events.h:44:30: note: in expansion of macro 'PARAMS'
      44 |                              PARAMS(assign),                   \
         |                              ^~~~~~
   include/trace/events/sched.h:775:1: note: in expansion of macro 'TRACE_EVENT'
     775 | TRACE_EVENT(sched_skip_cpuset_numa,
         | ^~~~~~~~~~~
   include/trace/events/sched.h:789:9: note: in expansion of macro 'TP_fast_assign'
     789 |         TP_fast_assign(
         |         ^~~~~~~~~~~~~~
   include/trace/events/sched.h:796:17: note: in expansion of macro 'get_task_array'
     796 |                 get_task_array(__entry->mem_allowed, mem_allowed_ptr->bits);
         |                 ^~~~~~~~~~~~~~
   include/linux/sched.h:1991:33: note: expected 'char *' but argument is of type 'long unsigned int *'
    1991 |         __cstr_array_copy(char *dst, const char *src,
         |                           ~~~~~~^~~
   include/trace/events/sched.h:796:69: error: passing argument 2 of '__cstr_array_copy' from incompatible pointer type [-Werror=incompatible-pointer-types]
     796 |                 get_task_array(__entry->mem_allowed, mem_allowed_ptr->bits);
         |                                                      ~~~~~~~~~~~~~~~^~~~~~
         |                                                                     |
         |                                                                     long unsigned int *
   include/trace/perf.h:51:11: note: in definition of macro '__DECLARE_EVENT_CLASS'
      51 |         { assign; }                                                     \
         |           ^~~~~~
   include/trace/perf.h:67:23: note: in expansion of macro 'PARAMS'
      67 |                       PARAMS(assign), PARAMS(print))                    \
         |                       ^~~~~~
   include/trace/trace_events.h:40:9: note: in expansion of macro 'DECLARE_EVENT_CLASS'
      40 |         DECLARE_EVENT_CLASS(name,                              \
         |         ^~~~~~~~~~~~~~~~~~~
   include/trace/trace_events.h:44:30: note: in expansion of macro 'PARAMS'
      44 |                              PARAMS(assign),                   \
         |                              ^~~~~~
   include/trace/events/sched.h:775:1: note: in expansion of macro 'TRACE_EVENT'
     775 | TRACE_EVENT(sched_skip_cpuset_numa,
         | ^~~~~~~~~~~
   include/trace/events/sched.h:789:9: note: in expansion of macro 'TP_fast_assign'
     789 |         TP_fast_assign(
         |         ^~~~~~~~~~~~~~
   include/trace/events/sched.h:796:17: note: in expansion of macro 'get_task_array'
     796 |                 get_task_array(__entry->mem_allowed, mem_allowed_ptr->bits);
         |                 ^~~~~~~~~~~~~~
   include/linux/sched.h:1991:50: note: expected 'const char *' but argument is of type 'long unsigned int *'
    1991 |         __cstr_array_copy(char *dst, const char *src,
         |                                      ~~~~~~~~~~~~^~~
   cc1: some warnings being treated as errors


vim +/__cstr_array_copy +796 include/trace/events/sched.h

   776	
   777		TP_PROTO(struct task_struct *tsk, nodemask_t *mem_allowed_ptr),
   778	
   779		TP_ARGS(tsk, mem_allowed_ptr),
   780	
   781		TP_STRUCT__entry(
   782			__array( char,		comm,		TASK_COMM_LEN		)
   783			__field( pid_t,		pid					)
   784			__field( pid_t,		tgid					)
   785			__field( pid_t,		ngid					)
   786			__array( unsigned long, mem_allowed, BITS_TO_LONGS(MAX_NUMNODES))
   787		),
   788	
   789		TP_fast_assign(
   790			get_task_array(__entry->comm, tsk->comm);
   791			__entry->pid		 = task_pid_nr(tsk);
   792			__entry->tgid		 = task_tgid_nr(tsk);
   793			__entry->ngid		 = task_numa_group_id(tsk);
   794			BUILD_BUG_ON(sizeof(nodemask_t) != \
   795				     BITS_TO_LONGS(MAX_NUMNODES) * sizeof(long));
 > 796			get_task_array(__entry->mem_allowed, mem_allowed_ptr->bits);
   797		),
   798	
   799		TP_printk("comm=%s pid=%d tgid=%d ngid=%d mem_nodes_allowed=%*pbl",
   800			  __entry->comm,
   801			  __entry->pid,
   802			  __entry->tgid,
   803			  __entry->ngid,
   804			  MAX_NUMNODES, __entry->mem_allowed)
   805	);
   806	#endif /* CONFIG_NUMA_BALANCING */
   807	
   808	/*
   809	 * Tracepoint for waking a polling cpu without an IPI.
   810	 */
   811	TRACE_EVENT(sched_wake_idle_without_ipi,
   812	
   813		TP_PROTO(int cpu),
   814	
   815		TP_ARGS(cpu),
   816	
   817		TP_STRUCT__entry(
   818			__field(	int,	cpu	)
   819		),
   820	
   821		TP_fast_assign(
   822			__entry->cpu	= cpu;
   823		),
   824	
   825		TP_printk("cpu=%d", __entry->cpu)
   826	);
   827	
   828	/*
   829	 * Following tracepoints are not exported in tracefs and provide hooking
   830	 * mechanisms only for testing and debugging purposes.
   831	 */
   832	DECLARE_TRACE(pelt_cfs,
   833		TP_PROTO(struct cfs_rq *cfs_rq),
   834		TP_ARGS(cfs_rq));
   835	
   836	DECLARE_TRACE(pelt_rt,
   837		TP_PROTO(struct rq *rq),
   838		TP_ARGS(rq));
   839	
   840	DECLARE_TRACE(pelt_dl,
   841		TP_PROTO(struct rq *rq),
   842		TP_ARGS(rq));
   843	
   844	DECLARE_TRACE(pelt_hw,
   845		TP_PROTO(struct rq *rq),
   846		TP_ARGS(rq));
   847	
   848	DECLARE_TRACE(pelt_irq,
   849		TP_PROTO(struct rq *rq),
   850		TP_ARGS(rq));
   851	
   852	DECLARE_TRACE(pelt_se,
   853		TP_PROTO(struct sched_entity *se),
   854		TP_ARGS(se));
   855	
   856	DECLARE_TRACE(sched_cpu_capacity,
   857		TP_PROTO(struct rq *rq),
   858		TP_ARGS(rq));
   859	
   860	DECLARE_TRACE(sched_overutilized,
   861		TP_PROTO(struct root_domain *rd, bool overutilized),
   862		TP_ARGS(rd, overutilized));
   863	
   864	DECLARE_TRACE(sched_util_est_cfs,
   865		TP_PROTO(struct cfs_rq *cfs_rq),
   866		TP_ARGS(cfs_rq));
   867	
   868	DECLARE_TRACE(sched_util_est_se,
   869		TP_PROTO(struct sched_entity *se),
   870		TP_ARGS(se));
   871	
   872	DECLARE_TRACE(sched_update_nr_running,
   873		TP_PROTO(struct rq *rq, int change),
   874		TP_ARGS(rq, change));
   875	
   876	DECLARE_TRACE(sched_compute_energy,
   877		TP_PROTO(struct task_struct *p, int dst_cpu, unsigned long energy,
   878			 unsigned long max_util, unsigned long busy_time),
   879		TP_ARGS(p, dst_cpu, energy, max_util, busy_time));
   880	
   881	DECLARE_TRACE(sched_entry,
   882		TP_PROTO(bool preempt),
   883		TP_ARGS(preempt));
   884	
   885	DECLARE_TRACE(sched_exit,
   886		TP_PROTO(bool is_switch),
   887		TP_ARGS(is_switch));
   888	
   889	DECLARE_TRACE_CONDITION(sched_set_state,
   890		TP_PROTO(struct task_struct *tsk, int state),
   891		TP_ARGS(tsk, state),
   892		TP_CONDITION(!!(tsk->__state) != !!state));
   893	
   894	DECLARE_TRACE(sched_set_need_resched,
   895		TP_PROTO(struct task_struct *tsk, int cpu, int tif),
   896		TP_ARGS(tsk, cpu, tif));
   897	
   898	#endif /* _TRACE_SCHED_H */
   899	
   900	/* This part must be outside protection */
 > 901	#include <trace/define_trace.h>

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki