From: Nikita Kiryushin kiryushin@ancud.ru

[ Upstream commit cc5645fddb0ce28492b15520306d092730dffa48 ]

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 Reviewed-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Paul E. McKenney paulmck@kernel.org Signed-off-by: Uladzislau Rezki (Sony) urezki@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Vamsi Krishna Brahmajosyula vamsi-krishna.brahmajosyula@broadcom.com --- 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 105fdc2bb004..bede3a4f108e 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -1240,7 +1240,7 @@ static void show_rcu_tasks_trace_gp_kthread(void) { char buf[64];

- sprintf(buf, "N%d h:%lu/%lu/%lu", atomic_read(&trc_n_readers_need_end), + snprintf(buf, sizeof(buf), "N%d h:%lu/%lu/%lu", atomic_read(&trc_n_readers_need_end), data_race(n_heavy_reader_ofl_updates), data_race(n_heavy_reader_updates), data_race(n_heavy_reader_attempts));