[for-next][PATCH 1/6] tracing/syscalls: Use copy_from_user for the faultable syscall buffer

[for-next][PATCH 1/6] tracing/syscalls: Use copy_from_user for the faultable syscall buffer

[Steven Rostedt]

From: Haoran Wang <haoranwangsec@gmail.com>

syscall_copy_user_array() copies the buffer argument of faultable
syscalls (write, pwrite64, ...) with __copy_from_user(), which skips
access_ok(). Use copy_from_user() instead so a non-user address is
rejected and the entry is recorded as faulted.

It could be a security concern for machines that trust perf a bit too
much.

Cc: stable@vger.kernel.org
Fixes: baa031b7bd2ce ("tracing: Allow syscall trace events to read more than one user parameter")
Link: https://patch.msgid.link/6ad19afd.a938ce27.16851e.3440@mx.google.com
Signed-off-by: Haoran Wang <haoranwangsec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_syscalls.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index e35744049e3f..d9190fdc030d 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -683,7 +683,7 @@ static int syscall_copy_user_array(char *buf, const char __user *ptr,
 
 	for (int i = 0; i < args->uargs; i++, buf += SYSCALL_FAULT_ARG_SZ) {
 		ptr = (char __user *)args->ptr_array[i];
-		ret = __copy_from_user(buf, ptr, size);
+		ret = copy_from_user(buf, ptr, size);
 		args->read[i] = ret ? -1 : size;
 	}
 	return 0;
-- 
2.53.0

[for-next][PATCH 2/6] tracing: Hold trace_types_lock when updating modules in persistent instances

[Steven Rostedt]

From: David Carlier <devnexen@gmail.com>

trace_module_record() walks ftrace_trace_arrays from the module notifier
without trace_types_lock. A concurrent rmdir of an instance removes it
from the list and frees it under that lock, so a module load or unload
can walk into a freed trace_array.

Cc: stable@vger.kernel.org
Fixes: 5f3719f697c3 ("tracing: Update modules to persistent instances when loaded")
Link: https://patch.msgid.link/20261016061638.214847-1-devnexen@gmail.com
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 48ecc4bb55e4..96005a930b25 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9244,6 +9244,8 @@ static void trace_module_record(struct module *mod, bool add)
 	struct trace_array *tr;
 	unsigned long flags;
 
+	guard(mutex)(&trace_types_lock);
+
 	list_for_each_entry(tr, &ftrace_trace_arrays, list) {
 		flags = tr->flags & (TRACE_ARRAY_FL_BOOT | TRACE_ARRAY_FL_LAST_BOOT);
 		/* Update any persistent trace array that has already been started */
-- 
2.53.0

[for-next][PATCH 3/6] tracing: Hold trace_types_lock when resetting last boot data from readers

[Steven Rostedt]

From: David Carlier <devnexen@gmail.com>

update_last_data_if_empty() is called from tracing_open() with O_TRUNC,
tracing_read_pipe() and tracing_buffers_read() without trace_types_lock.
Two readers can both pass the LAST_BOOT test and free module_delta
twice, and a module notifier can update module_delta while it is being
freed.

Take trace_types_lock in those paths and keep the callers that already
hold it on an unlocked variant.

Cc: stable@vger.kernel.org
Fixes: 32dc0042528d ("tracing: Reset last-boot buffers when reading out all cpu buffers")
Link: https://patch.msgid.link/20261016061638.214847-2-devnexen@gmail.com
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 96005a930b25..08614af8fad1 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3603,6 +3603,7 @@ static int tracing_single_release_tr(struct inode *inode, struct file *file)
 	return single_release(inode, file);
 }
 
+static bool __update_last_data_if_empty(struct trace_array *tr);
 static bool update_last_data_if_empty(struct trace_array *tr);
 
 static int tracing_open(struct inode *inode, struct file *file)
@@ -4697,7 +4698,7 @@ tracing_set_trace_read(struct file *filp, char __user *ubuf,
 int tracer_init(struct tracer *t, struct trace_array *tr)
 {
 	tracing_reset_online_cpus(&tr->array_buffer);
-	update_last_data_if_empty(tr);
+	__update_last_data_if_empty(tr);
 	return t->init(tr);
 }
 
@@ -5371,8 +5372,10 @@ static int tracing_wait_pipe(struct file *filp)
 	return 1;
 }
 
-static bool update_last_data_if_empty(struct trace_array *tr)
+static bool __update_last_data_if_empty(struct trace_array *tr)
 {
+	lockdep_assert_held(&trace_types_lock);
+
 	if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT))
 		return false;
 
@@ -5387,6 +5390,16 @@ static bool update_last_data_if_empty(struct trace_array *tr)
 	return true;
 }
 
+static bool update_last_data_if_empty(struct trace_array *tr)
+{
+	/* Avoid the lock on the read path unless this is a last boot buffer */
+	if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT))
+		return false;
+
+	guard(mutex)(&trace_types_lock);
+	return __update_last_data_if_empty(tr);
+}
+
 /*
  * Consumer reader.
  */
@@ -6476,7 +6489,7 @@ int tracing_set_clock(struct trace_array *tr, const char *clockstr)
 		ring_buffer_set_clock(tr->snapshot_buffer.buffer, trace_clocks[i].func);
 	tracing_reset_online_cpus(&tr->snapshot_buffer);
 #endif
-	update_last_data_if_empty(tr);
+	__update_last_data_if_empty(tr);
 
 	if (tr->scratch && !(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) {
 		struct trace_scratch *tscratch = tr->scratch;
-- 
2.53.0

[for-next][PATCH 4/6] tracing: Save the event file instead of the compatible histogram

[Steven Rostedt]

From: Donggeun Yoo <donggeunyoo.kernel@gmail.com>

create_field_var_hist() creates a histogram on the matched event to
supply a field variable, and records it on the target so it can be torn
down later:

	hist_data = find_compatible_hist(target_hist_data, file);
	...
	/* Save the compatible histogram information */
	var_hist->hist_data = hist_data;

hist_data is not the histogram it creates. It is one that was already
there, whose keys the new one copies. The saved pointer has a single
user, unregister_field_var_hists(), which runs when the target is
removed:

	file = hist_data->field_var_hists[i]->hist_data->event_file;

find_compatible_hist() matches on keys alone, so it can pick one with no
variables of its own. check_var_refs() then returns false and the user
can remove it while the target still points at it:

 BUG: KASAN: slab-use-after-free in event_hist_trigger_free+0x2b2/0x320
 Read of size 8 at addr ffff8880093b90e0 by task init/1

 Freed by task 1:
  kfree+0x154/0x420
  event_hist_trigger_free+0x1d5/0x320
  event_hist_trigger_parse+0x35f3/0x69e0
  trigger_process_regex+0x1a6/0x250

Save the event file instead. It is all the dereference ever wanted, and
it does not go away when the user removes a trigger.

Cc: stable@vger.kernel.org
Reported-by: Sashiko <sashiko-bot@kernel.org>
Link: https://lore.kernel.org/all/20260914110753.221E61F000FF@smtp.kernel.org/
Link: https://patch.msgid.link/20260914234754.3676905-1-donggeunyoo.kernel@gmail.com
Fixes: 02205a6752f2 ("tracing: Add support for 'field variables'")
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Assisted-by: Claude:claude-fable-5
Acked-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_events_hist.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 5527605758cb..42b89171134d 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -557,7 +557,7 @@ struct field_var {
 };
 
 struct field_var_hist {
-	struct hist_trigger_data	*hist_data;
+	struct trace_event_file		*file;
 	char				*cmd;
 };
 
@@ -3129,8 +3129,8 @@ create_field_var_hist(struct hist_trigger_data *target_hist_data,
 		return ERR_PTR(-ENOMEM);
 	}
 
-	/* Save the compatible histogram information */
-	var_hist->hist_data = hist_data;
+	/* Needed to remove the histogram when the target goes away */
+	var_hist->file = file;
 
 	/* Create the new histogram with our variable */
 	ret = event_hist_trigger_parse(&trigger_hist_cmd, file,
@@ -6362,7 +6362,7 @@ static void unregister_field_var_hists(struct hist_trigger_data *hist_data)
 	int ret;
 
 	for (i = 0; i < hist_data->n_field_var_hists; i++) {
-		file = hist_data->field_var_hists[i]->hist_data->event_file;
+		file = hist_data->field_var_hists[i]->file;
 		cmd = hist_data->field_var_hists[i]->cmd;
 		ret = event_hist_trigger_parse(&trigger_hist_cmd, file,
 					       "!hist", "hist", cmd);
-- 
2.53.0

[for-next][PATCH 5/6] tracing/histograms: Verify event_call identity when updating synth_event refcount

[Steven Rostedt]

From: Lee Jones <lee@kernel.org>

In event_hist_trigger_parse() and hist_unreg_all(), the histogram
registration and unregistration paths look up find_synth_event() using
trace_event_name(file->event_call) and adjust se->ref if a match is
found.

Because find_synth_event() only compares the event basename, registering
or removing a histogram on a non-synthetic trace event whose basename
matches a synthetic event erroneously modifies the synthetic event's
reference count.  If a histogram is registered on the non-synthetic
event before the synthetic event is created and removed afterwards,
se->ref is decremented without a matching increment, allowing the
synthetic event to be freed while an active histogram action still holds
a pointer to it.

Introduce find_synth_event_call() to verify that &se->call matches
file->event_call before adjusting se->ref.

Fixes: 4b147936fa50 ("tracing: Add support for 'synthetic' events")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20261019120730.2342739-1-lee@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_events_hist.c  | 11 +++--------
 kernel/trace/trace_events_synth.c | 10 ++++++++++
 kernel/trace/trace_synth.h        |  1 +
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 42b89171134d..f39fa8942673 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -6812,7 +6812,6 @@ static void hist_unreg_all(struct trace_event_file *file)
 	struct event_trigger_data *test, *n;
 	struct hist_trigger_data *hist_data;
 	struct synth_event *se;
-	const char *se_name;
 
 	lockdep_assert_held(&event_mutex);
 
@@ -6825,8 +6824,7 @@ static void hist_unreg_all(struct trace_event_file *file)
 			list_del_rcu(&test->list);
 			trace_event_trigger_enable_disable(file, 0);
 
-			se_name = trace_event_name(file->event_call);
-			se = find_synth_event(se_name);
+			se = find_synth_event_call(file->event_call);
 			if (se)
 				se->ref--;
 
@@ -6850,7 +6848,6 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
 	struct hist_trigger_data *hist_data;
 	char *param, *filter, *p, *start;
 	struct synth_event *se;
-	const char *se_name;
 	bool remove;
 	int ret = 0;
 
@@ -6944,8 +6941,7 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
 		}
 
 		event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
-		se_name = trace_event_name(file->event_call);
-		se = find_synth_event(se_name);
+		se = find_synth_event_call(file->event_call);
 		if (se)
 			se->ref--;
 		ret = 0;
@@ -6980,8 +6976,7 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
 	if (ret)
 		goto out_unreg;
 
-	se_name = trace_event_name(file->event_call);
-	se = find_synth_event(se_name);
+	se = find_synth_event_call(file->event_call);
 	if (se)
 		se->ref++;
  out:
diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index dc15658a887c..e2870212e58d 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -914,6 +914,16 @@ struct synth_event *find_synth_event(const char *name)
 	return NULL;
 }
 
+struct synth_event *find_synth_event_call(struct trace_event_call *call)
+{
+	struct synth_event *se;
+	const char *name;
+
+	name = trace_event_name(call);
+	se = find_synth_event(name);
+	return se && &se->call == call ? se : NULL;
+}
+
 static struct trace_event_fields synth_event_fields_array[] = {
 	{ .type = TRACE_FUNCTION_TYPE,
 	  .define_fields = synth_event_define_fields },
diff --git a/kernel/trace/trace_synth.h b/kernel/trace/trace_synth.h
index 43f6fb6078db..d4ebf01b7049 100644
--- a/kernel/trace/trace_synth.h
+++ b/kernel/trace/trace_synth.h
@@ -37,5 +37,6 @@ struct synth_event {
 };
 
 extern struct synth_event *find_synth_event(const char *name);
+extern struct synth_event *find_synth_event_call(struct trace_event_call *call);
 
 #endif /* __TRACE_SYNTH_H */
-- 
2.53.0