* Re: [PATCH 1/7] binder: fix alloc->vma_vm_mm null-ptr dereference
2022-08-29 20:12 ` [PATCH 1/7] binder: fix alloc->vma_vm_mm null-ptr dereference Carlos Llamas
@ 2022-08-29 20:34 ` Andrew Morton
2022-08-29 21:20 ` Carlos Llamas
2022-08-30 19:06 ` Liam Howlett
2022-08-30 22:26 ` Todd Kjos
2 siblings, 1 reply; 7+ messages in thread
From: Andrew Morton @ 2022-08-29 20:34 UTC (permalink / raw)
To: Carlos Llamas
Cc: Greg Kroah-Hartman, Arve Hjønnevåg , Todd Kjos,
Martijn Coenen, Joel Fernandes, Christian Brauner,
Suren Baghdasaryan, Liam Howlett, kernel-team,
syzbot+f7dc54e5be28950ac459, syzbot+a75ebe0452711c9e56d9, stable,
Liam R . Howlett, linux-kernel
On Mon, 29 Aug 2022 20:12:48 +0000 Carlos Llamas <cmllamas@google.com> wrote:
> Syzbot reported a couple issues introduced by commit 44e602b4e52f
> ("binder_alloc: add missing mmap_lock calls when using the VMA"), in
> which we attempt to acquire the mmap_lock when alloc->vma_vm_mm has not
> been initialized yet.
>
> This can happen if a binder_proc receives a transaction without having
> previously called mmap() to setup the binder_proc->alloc space in [1].
> Also, a similar issue occurs via binder_alloc_print_pages() when we try
> to dump the debugfs binder stats file in [2].
Thanks. I assume you'll be merging all these into mainline?
>
> Fixes: 44e602b4e52f ("binder_alloc: add missing mmap_lock calls when using the VMA")
> Reported-by: syzbot+f7dc54e5be28950ac459@syzkaller.appspotmail.com
> Reported-by: syzbot+a75ebe0452711c9e56d9@syzkaller.appspotmail.com
> Cc: <stable@vger.kernel.org> # v5.15+
44e602b4e52f is only present in 6.0-rcX?
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 1/7] binder: fix alloc->vma_vm_mm null-ptr dereference
2022-08-29 20:34 ` Andrew Morton
@ 2022-08-29 21:20 ` Carlos Llamas
0 siblings, 0 replies; 7+ messages in thread
From: Carlos Llamas @ 2022-08-29 21:20 UTC (permalink / raw)
To: Andrew Morton
Cc: Greg Kroah-Hartman, Arve Hjønnevåg, Todd Kjos,
Martijn Coenen, Joel Fernandes, Christian Brauner,
Suren Baghdasaryan, Liam Howlett, kernel-team,
syzbot+f7dc54e5be28950ac459, syzbot+a75ebe0452711c9e56d9, stable,
linux-kernel
On Mon, Aug 29, 2022 at 01:34:52PM -0700, Andrew Morton wrote:
> On Mon, 29 Aug 2022 20:12:48 +0000 Carlos Llamas <cmllamas@google.com> wrote:
>
> > Syzbot reported a couple issues introduced by commit 44e602b4e52f
> > ("binder_alloc: add missing mmap_lock calls when using the VMA"), in
> > which we attempt to acquire the mmap_lock when alloc->vma_vm_mm has not
> > been initialized yet.
> >
> > This can happen if a binder_proc receives a transaction without having
> > previously called mmap() to setup the binder_proc->alloc space in [1].
> > Also, a similar issue occurs via binder_alloc_print_pages() when we try
> > to dump the debugfs binder stats file in [2].
>
> Thanks. I assume you'll be merging all these into mainline?
Yes, I believe Greg will pick up these patches into his char-misc tree.
>
> >
> > Fixes: 44e602b4e52f ("binder_alloc: add missing mmap_lock calls when using the VMA")
> > Reported-by: syzbot+f7dc54e5be28950ac459@syzkaller.appspotmail.com
> > Reported-by: syzbot+a75ebe0452711c9e56d9@syzkaller.appspotmail.com
> > Cc: <stable@vger.kernel.org> # v5.15+
>
> 44e602b4e52f is only present in 6.0-rcX?
Right, it was just added to the stable queue earlier today:
https://lore.kernel.org/all/20220829105814.857786586@linuxfoundation.org/
https://lore.kernel.org/all/20220829105809.855177179@linuxfoundation.org/
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/7] binder: fix alloc->vma_vm_mm null-ptr dereference
2022-08-29 20:12 ` [PATCH 1/7] binder: fix alloc->vma_vm_mm null-ptr dereference Carlos Llamas
2022-08-29 20:34 ` Andrew Morton
@ 2022-08-30 19:06 ` Liam Howlett
2022-08-30 19:40 ` Carlos Llamas
2022-08-30 22:26 ` Todd Kjos
2 siblings, 1 reply; 7+ messages in thread
From: Liam Howlett @ 2022-08-30 19:06 UTC (permalink / raw)
To: Carlos Llamas
Cc: Greg Kroah-Hartman, Arve Hjønnevåg, Todd Kjos,
Martijn Coenen, Joel Fernandes, Christian Brauner,
Suren Baghdasaryan, Andrew Morton, kernel-team@android.com,
syzbot+f7dc54e5be28950ac459@syzkaller.appspotmail.com,
syzbot+a75ebe0452711c9e56d9@syzkaller.appspotmail.com,
stable@vger.kernel.org, linux-kernel@vger.kernel.org
* Carlos Llamas <cmllamas@google.com> [220829 16:13]:
> Syzbot reported a couple issues introduced by commit 44e602b4e52f
> ("binder_alloc: add missing mmap_lock calls when using the VMA"), in
> which we attempt to acquire the mmap_lock when alloc->vma_vm_mm has not
> been initialized yet.
>
> This can happen if a binder_proc receives a transaction without having
> previously called mmap() to setup the binder_proc->alloc space in [1].
> Also, a similar issue occurs via binder_alloc_print_pages() when we try
> to dump the debugfs binder stats file in [2].
>
> Sample of syzbot's crash report:
> ==================================================================
> KASAN: null-ptr-deref in range [0x0000000000000128-0x000000000000012f]
> CPU: 0 PID: 3755 Comm: syz-executor229 Not tainted 6.0.0-rc1-next-20220819-syzkaller #0
> syz-executor229[3755] cmdline: ./syz-executor2294415195
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
> RIP: 0010:__lock_acquire+0xd83/0x56d0 kernel/locking/lockdep.c:4923
> [...]
> Call Trace:
> <TASK>
> lock_acquire kernel/locking/lockdep.c:5666 [inline]
> lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631
> down_read+0x98/0x450 kernel/locking/rwsem.c:1499
> mmap_read_lock include/linux/mmap_lock.h:117 [inline]
> binder_alloc_new_buf_locked drivers/android/binder_alloc.c:405 [inline]
> binder_alloc_new_buf+0xa5/0x19e0 drivers/android/binder_alloc.c:593
> binder_transaction+0x242e/0x9a80 drivers/android/binder.c:3199
> binder_thread_write+0x664/0x3220 drivers/android/binder.c:3986
> binder_ioctl_write_read drivers/android/binder.c:5036 [inline]
> binder_ioctl+0x3470/0x6d00 drivers/android/binder.c:5323
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:870 [inline]
> __se_sys_ioctl fs/ioctl.c:856 [inline]
> __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
> [...]
> ==================================================================
>
> Fix these issues by setting up alloc->vma_vm_mm pointer during open()
> and caching directly from current->mm. This guarantees we have a valid
> reference to take the mmap_lock during scenarios described above.
>
> [1] https://syzkaller.appspot.com/bug?extid=f7dc54e5be28950ac459
> [2] https://syzkaller.appspot.com/bug?extid=a75ebe0452711c9e56d9
>
> Fixes: 44e602b4e52f ("binder_alloc: add missing mmap_lock calls when using the VMA")
> Reported-by: syzbot+f7dc54e5be28950ac459@syzkaller.appspotmail.com
> Reported-by: syzbot+a75ebe0452711c9e56d9@syzkaller.appspotmail.com
> Cc: <stable@vger.kernel.org> # v5.15+
> Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
> Signed-off-by: Carlos Llamas <cmllamas@google.com>
> ---
> drivers/android/binder_alloc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
> index 51f4e1c5cd01..9b1778c00610 100644
> --- a/drivers/android/binder_alloc.c
> +++ b/drivers/android/binder_alloc.c
> @@ -322,7 +322,6 @@ static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
> */
> if (vma) {
> vm_start = vma->vm_start;
> - alloc->vma_vm_mm = vma->vm_mm;
Is this really the null pointer dereference? We check for vma above..?
> mmap_assert_write_locked(alloc->vma_vm_mm);
> } else {
> mmap_assert_locked(alloc->vma_vm_mm);
> @@ -795,7 +794,6 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc,
> binder_insert_free_buffer(alloc, buffer);
> alloc->free_async_space = alloc->buffer_size / 2;
> binder_alloc_set_vma(alloc, vma);
> - mmgrab(alloc->vma_vm_mm);
>
> return 0;
>
> @@ -1091,6 +1089,8 @@ static struct shrinker binder_shrinker = {
> void binder_alloc_init(struct binder_alloc *alloc)
> {
> alloc->pid = current->group_leader->pid;
> + alloc->vma_vm_mm = current->mm;
> + mmgrab(alloc->vma_vm_mm);
> mutex_init(&alloc->mutex);
> INIT_LIST_HEAD(&alloc->buffers);
> }
> --
> 2.37.2.672.g94769d06f0-goog
>
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 1/7] binder: fix alloc->vma_vm_mm null-ptr dereference
2022-08-30 19:06 ` Liam Howlett
@ 2022-08-30 19:40 ` Carlos Llamas
2022-08-30 20:30 ` Liam Howlett
0 siblings, 1 reply; 7+ messages in thread
From: Carlos Llamas @ 2022-08-30 19:40 UTC (permalink / raw)
To: Liam Howlett
Cc: Greg Kroah-Hartman, Arve Hjønnevåg, Todd Kjos,
Martijn Coenen, Joel Fernandes, Christian Brauner,
Suren Baghdasaryan, Andrew Morton, kernel-team@android.com,
syzbot+f7dc54e5be28950ac459@syzkaller.appspotmail.com,
syzbot+a75ebe0452711c9e56d9@syzkaller.appspotmail.com,
stable@vger.kernel.org, linux-kernel@vger.kernel.org
On Tue, Aug 30, 2022 at 07:06:37PM +0000, Liam Howlett wrote:
> > diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
> > index 51f4e1c5cd01..9b1778c00610 100644
> > --- a/drivers/android/binder_alloc.c
> > +++ b/drivers/android/binder_alloc.c
> > @@ -322,7 +322,6 @@ static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
> > */
> > if (vma) {
> > vm_start = vma->vm_start;
> > - alloc->vma_vm_mm = vma->vm_mm;
>
> Is this really the null pointer dereference? We check for vma above..?
>
Not here. The sequence leading to the null-ptr-deref happens when we try
to take alloc->vma_vm_mm->mmap_lock in binder_alloc_new_buf_locked() and
in binder_alloc_print_pages() without initializing alloc->vma_vm_mm
first (e.g. mmap() was never called). These sequences are described in
the commit message but basically they translate to mmap_read_lock(NULL)
calls.
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 1/7] binder: fix alloc->vma_vm_mm null-ptr dereference
2022-08-30 19:40 ` Carlos Llamas
@ 2022-08-30 20:30 ` Liam Howlett
0 siblings, 0 replies; 7+ messages in thread
From: Liam Howlett @ 2022-08-30 20:30 UTC (permalink / raw)
To: Carlos Llamas
Cc: Greg Kroah-Hartman, Arve Hjønnevåg, Todd Kjos,
Martijn Coenen, Joel Fernandes, Christian Brauner,
Suren Baghdasaryan, Andrew Morton, kernel-team@android.com,
syzbot+f7dc54e5be28950ac459@syzkaller.appspotmail.com,
syzbot+a75ebe0452711c9e56d9@syzkaller.appspotmail.com,
stable@vger.kernel.org, linux-kernel@vger.kernel.org
* Carlos Llamas <cmllamas@google.com> [220830 15:41]:
> On Tue, Aug 30, 2022 at 07:06:37PM +0000, Liam Howlett wrote:
> > > diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
> > > index 51f4e1c5cd01..9b1778c00610 100644
> > > --- a/drivers/android/binder_alloc.c
> > > +++ b/drivers/android/binder_alloc.c
> > > @@ -322,7 +322,6 @@ static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
> > > */
> > > if (vma) {
> > > vm_start = vma->vm_start;
> > > - alloc->vma_vm_mm = vma->vm_mm;
> >
> > Is this really the null pointer dereference? We check for vma above..?
> >
>
> Not here. The sequence leading to the null-ptr-deref happens when we try
> to take alloc->vma_vm_mm->mmap_lock in binder_alloc_new_buf_locked() and
> in binder_alloc_print_pages() without initializing alloc->vma_vm_mm
> first (e.g. mmap() was never called). These sequences are described in
> the commit message but basically they translate to mmap_read_lock(NULL)
> calls.
Ah, this is unnecessary with the rest of the change.
Feel free to add my reviewed-by if you want.
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/7] binder: fix alloc->vma_vm_mm null-ptr dereference
2022-08-29 20:12 ` [PATCH 1/7] binder: fix alloc->vma_vm_mm null-ptr dereference Carlos Llamas
2022-08-29 20:34 ` Andrew Morton
2022-08-30 19:06 ` Liam Howlett
@ 2022-08-30 22:26 ` Todd Kjos
2 siblings, 0 replies; 7+ messages in thread
From: Todd Kjos @ 2022-08-30 22:26 UTC (permalink / raw)
To: Carlos Llamas
Cc: Greg Kroah-Hartman, Arve Hjønnevåg, Todd Kjos,
Martijn Coenen, Joel Fernandes, Christian Brauner,
Suren Baghdasaryan, Andrew Morton, Liam Howlett, kernel-team,
syzbot+f7dc54e5be28950ac459, syzbot+a75ebe0452711c9e56d9, stable,
linux-kernel
On Mon, Aug 29, 2022 at 1:13 PM 'Carlos Llamas' via kernel-team
<kernel-team@android.com> wrote:
>
> Syzbot reported a couple issues introduced by commit 44e602b4e52f
> ("binder_alloc: add missing mmap_lock calls when using the VMA"), in
> which we attempt to acquire the mmap_lock when alloc->vma_vm_mm has not
> been initialized yet.
>
> This can happen if a binder_proc receives a transaction without having
> previously called mmap() to setup the binder_proc->alloc space in [1].
> Also, a similar issue occurs via binder_alloc_print_pages() when we try
> to dump the debugfs binder stats file in [2].
>
> Sample of syzbot's crash report:
> ==================================================================
> KASAN: null-ptr-deref in range [0x0000000000000128-0x000000000000012f]
> CPU: 0 PID: 3755 Comm: syz-executor229 Not tainted 6.0.0-rc1-next-20220819-syzkaller #0
> syz-executor229[3755] cmdline: ./syz-executor2294415195
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
> RIP: 0010:__lock_acquire+0xd83/0x56d0 kernel/locking/lockdep.c:4923
> [...]
> Call Trace:
> <TASK>
> lock_acquire kernel/locking/lockdep.c:5666 [inline]
> lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631
> down_read+0x98/0x450 kernel/locking/rwsem.c:1499
> mmap_read_lock include/linux/mmap_lock.h:117 [inline]
> binder_alloc_new_buf_locked drivers/android/binder_alloc.c:405 [inline]
> binder_alloc_new_buf+0xa5/0x19e0 drivers/android/binder_alloc.c:593
> binder_transaction+0x242e/0x9a80 drivers/android/binder.c:3199
> binder_thread_write+0x664/0x3220 drivers/android/binder.c:3986
> binder_ioctl_write_read drivers/android/binder.c:5036 [inline]
> binder_ioctl+0x3470/0x6d00 drivers/android/binder.c:5323
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:870 [inline]
> __se_sys_ioctl fs/ioctl.c:856 [inline]
> __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
> [...]
> ==================================================================
>
> Fix these issues by setting up alloc->vma_vm_mm pointer during open()
> and caching directly from current->mm. This guarantees we have a valid
> reference to take the mmap_lock during scenarios described above.
>
> [1] https://syzkaller.appspot.com/bug?extid=f7dc54e5be28950ac459
> [2] https://syzkaller.appspot.com/bug?extid=a75ebe0452711c9e56d9
>
> Fixes: 44e602b4e52f ("binder_alloc: add missing mmap_lock calls when using the VMA")
> Reported-by: syzbot+f7dc54e5be28950ac459@syzkaller.appspotmail.com
> Reported-by: syzbot+a75ebe0452711c9e56d9@syzkaller.appspotmail.com
> Cc: <stable@vger.kernel.org> # v5.15+
> Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
> Signed-off-by: Carlos Llamas <cmllamas@google.com>
Acked-by: Todd Kjos <tkjos@google.com>
> ---
> drivers/android/binder_alloc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
> index 51f4e1c5cd01..9b1778c00610 100644
> --- a/drivers/android/binder_alloc.c
> +++ b/drivers/android/binder_alloc.c
> @@ -322,7 +322,6 @@ static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
> */
> if (vma) {
> vm_start = vma->vm_start;
> - alloc->vma_vm_mm = vma->vm_mm;
> mmap_assert_write_locked(alloc->vma_vm_mm);
> } else {
> mmap_assert_locked(alloc->vma_vm_mm);
> @@ -795,7 +794,6 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc,
> binder_insert_free_buffer(alloc, buffer);
> alloc->free_async_space = alloc->buffer_size / 2;
> binder_alloc_set_vma(alloc, vma);
> - mmgrab(alloc->vma_vm_mm);
>
> return 0;
>
> @@ -1091,6 +1089,8 @@ static struct shrinker binder_shrinker = {
> void binder_alloc_init(struct binder_alloc *alloc)
> {
> alloc->pid = current->group_leader->pid;
> + alloc->vma_vm_mm = current->mm;
> + mmgrab(alloc->vma_vm_mm);
> mutex_init(&alloc->mutex);
> INIT_LIST_HEAD(&alloc->buffers);
> }
> --
> 2.37.2.672.g94769d06f0-goog
>
> --
> To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com.
>
^ permalink raw reply [flat|nested] 7+ messages in thread