On Wed, 27 Mar 2024 20:47:47 +0300
Nikita Kiryushin <kiryushin@xxxxxxxx> 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@xxxxxxxxxxx>
-- 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@xxxxxxxx>
> ---
> v4: Change ARRAY_SIZE to sizeof() as more idiomatic
> as Steven Rostedt <rostedt@xxxxxxxxxxx> suggested
> v3: Fixed commit message
> v2: Use snprintf() as
> Steven Rostedt <rostedt@xxxxxxxxxxx> 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),
