diff mbox series

[v4] rcu-tasks: Fix show_rcu_tasks_trace_gp_kthread buffer overflow

Message ID 20240327174747.612002-1-kiryushin@ancud.ru (mailing list archive)
State Accepted
Commit cb85f6247a6e1cbb10536eb5ae7055de07051944
Headers show
Series [v4] rcu-tasks: Fix show_rcu_tasks_trace_gp_kthread buffer overflow | expand

Commit Message

Nikita Kiryushin March 27, 2024, 5:47 p.m. UTC
There is a possibility of buffer overflow in
show_rcu_tasks_trace_gp_kthread() if counters, passed
to sprintf() are huge. Counter numbers, needed for this
are unrealistically high, but buffer overflow is still
possible.

Use snprintf() with buffer size instead of sprintf().

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: edf3775f0ad6 ("rcu-tasks: Add count for idle tasks on offline CPUs")
Signed-off-by: Nikita Kiryushin <kiryushin@ancud.ru>
---
v4: Change ARRAY_SIZE to sizeof() as more idiomatic
as Steven Rostedt <rostedt@goodmis.org> suggested
v3: Fixed commit message
v2: Use snprintf() as
Steven Rostedt <rostedt@goodmis.org> suggested.
 kernel/rcu/tasks.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Steven Rostedt March 27, 2024, 5:52 p.m. UTC | #1
On Wed, 27 Mar 2024 20:47:47 +0300
Nikita Kiryushin <kiryushin@ancud.ru> wrote:

> There is a possibility of buffer overflow in
> show_rcu_tasks_trace_gp_kthread() if counters, passed
> to sprintf() are huge. Counter numbers, needed for this
> are unrealistically high, but buffer overflow is still
> possible.
> 
> Use snprintf() with buffer size instead of sprintf().
> 

Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>

-- Steve

> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: edf3775f0ad6 ("rcu-tasks: Add count for idle tasks on offline CPUs")
> Signed-off-by: Nikita Kiryushin <kiryushin@ancud.ru>
> ---
> v4: Change ARRAY_SIZE to sizeof() as more idiomatic
> as Steven Rostedt <rostedt@goodmis.org> suggested
> v3: Fixed commit message
> v2: Use snprintf() as
> Steven Rostedt <rostedt@goodmis.org> suggested.
>  kernel/rcu/tasks.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> index 147b5945d67a..2a453de9f3d9 100644
> --- a/kernel/rcu/tasks.h
> +++ b/kernel/rcu/tasks.h
> @@ -1994,7 +1994,7 @@ void show_rcu_tasks_trace_gp_kthread(void)
>  {
>  	char buf[64];
>  
> -	sprintf(buf, "N%lu h:%lu/%lu/%lu",
> +	snprintf(buf, sizeof(buf), "N%lu h:%lu/%lu/%lu",
>  		data_race(n_trc_holdouts),
>  		data_race(n_heavy_reader_ofl_updates),
>  		data_race(n_heavy_reader_updates),
Paul E. McKenney March 27, 2024, 6:31 p.m. UTC | #2
On Wed, Mar 27, 2024 at 01:52:46PM -0400, Steven Rostedt wrote:
> On Wed, 27 Mar 2024 20:47:47 +0300
> Nikita Kiryushin <kiryushin@ancud.ru> wrote:
> 
> > There is a possibility of buffer overflow in
> > show_rcu_tasks_trace_gp_kthread() if counters, passed
> > to sprintf() are huge. Counter numbers, needed for this
> > are unrealistically high, but buffer overflow is still
> > possible.
> > 
> > Use snprintf() with buffer size instead of sprintf().
> > 
> 
> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Queued and pushed, thank you both!

							Thanx, Paul

> -- Steve
> 
> > Found by Linux Verification Center (linuxtesting.org) with SVACE.
> > 
> > Fixes: edf3775f0ad6 ("rcu-tasks: Add count for idle tasks on offline CPUs")
> > Signed-off-by: Nikita Kiryushin <kiryushin@ancud.ru>
> > ---
> > v4: Change ARRAY_SIZE to sizeof() as more idiomatic
> > as Steven Rostedt <rostedt@goodmis.org> suggested
> > v3: Fixed commit message
> > v2: Use snprintf() as
> > Steven Rostedt <rostedt@goodmis.org> suggested.
> >  kernel/rcu/tasks.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > index 147b5945d67a..2a453de9f3d9 100644
> > --- a/kernel/rcu/tasks.h
> > +++ b/kernel/rcu/tasks.h
> > @@ -1994,7 +1994,7 @@ void show_rcu_tasks_trace_gp_kthread(void)
> >  {
> >  	char buf[64];
> >  
> > -	sprintf(buf, "N%lu h:%lu/%lu/%lu",
> > +	snprintf(buf, sizeof(buf), "N%lu h:%lu/%lu/%lu",
> >  		data_race(n_trc_holdouts),
> >  		data_race(n_heavy_reader_ofl_updates),
> >  		data_race(n_heavy_reader_updates),
>
diff mbox series

Patch

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 147b5945d67a..2a453de9f3d9 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1994,7 +1994,7 @@  void show_rcu_tasks_trace_gp_kthread(void)
 {
 	char buf[64];
 
-	sprintf(buf, "N%lu h:%lu/%lu/%lu",
+	snprintf(buf, sizeof(buf), "N%lu h:%lu/%lu/%lu",
 		data_race(n_trc_holdouts),
 		data_race(n_heavy_reader_ofl_updates),
 		data_race(n_heavy_reader_updates),