[PATCH 6.1 080/473] rcu-tasks: Fix show_rcu_tasks_trace_gp_kthread buffer overflow

Greg Kroah-Hartman
2024-06-06T14:13:22Z

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>
---
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 b5d5b6cf093a7..6f48f565e3acb 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1789,7 +1789,7 @@ 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),
--
2.43.0