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[PATCH v2] rcu-tasks: Update show_rcu_tasks_trace_gp_kthread buffer size

Nikita Kiryushin posted 1 patch 1 year, 10 months ago 
kernel/rcu/tasks.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
[PATCH v2] rcu-tasks: Update show_rcu_tasks_trace_gp_kthread buffer size
Posted by Nikita Kiryushin 1 year, 10 months ago 
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>
---
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..963ecae3c8e6 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, ARRAY_SIZE(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),
-- 
2.34.1
Re: [PATCH v2] rcu-tasks: Update show_rcu_tasks_trace_gp_kthread buffer size
Posted by Steven Rostedt 1 year, 10 months ago 
On Wed, 27 Mar 2024 19:36:56 +0300
Nikita Kiryushin <kiryushin@ancud.ru> wrote:

> diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> index 147b5945d67a..963ecae3c8e6 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, ARRAY_SIZE(buf), "N%lu h:%lu/%lu/%lu",

Nit, but I would have used sizeof(buf) instead of ARRAY_SIZE(buf) as that's
more common practice for this type of code.

[ do a: git grep 'sizeof(buf)' ]

-- Steve

>  		data_race(n_trc_holdouts),
>  		data_race(n_heavy_reader_ofl_updates),
>  		data_race(n_heavy_reader_updates),
[PATCH v4] rcu-tasks: Fix show_rcu_tasks_trace_gp_kthread buffer overflow
Posted by Nikita Kiryushin 1 year, 10 months ago 
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(-)

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),
-- 
2.34.1
Re: [PATCH v4] rcu-tasks: Fix show_rcu_tasks_trace_gp_kthread buffer overflow
Posted by Steven Rostedt 1 year, 10 months ago 
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),
Re: [PATCH v4] rcu-tasks: Fix show_rcu_tasks_trace_gp_kthread buffer overflow
Posted by Paul E. McKenney 1 year, 10 months ago 
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),
>
[PATCH v3] rcu-tasks: Fix show_rcu_tasks_trace_gp_kthread buffer overflow
Posted by Nikita Kiryushin 1 year, 10 months ago 
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>
---
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..963ecae3c8e6 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, ARRAY_SIZE(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),
-- 
2.34.1

Patchew 2.1-devel-b67e4c2

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