Nikita Kiryushin e2228ed3fe rcu: Fix buffer overflow in print_cpu_stall_info()
[ Upstream commit 3758f7d9917bd7ef0482c4184c0ad673b4c4e069 ]

The rcuc-starvation output from print_cpu_stall_info() might overflow the
buffer if there is a huge difference in jiffies difference.  The situation
might seem improbable, but computers sometimes get very confused about
time, which can result in full-sized integers, and, in this case,
buffer overflow.

Also, the unsigned jiffies difference is printed using %ld, which is
normally for signed integers.  This is intentional for debugging purposes,
but it is not obvious from the code.

This commit therefore changes sprintf() to snprintf() and adds a
clarifying comment about intention of %ld format.

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

Fixes: 245a62982502 ("rcu: Dump rcuc kthread status for CPUs not reporting quiescent state")
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>
2024-06-12 11:03:05 +02:00
..
2020-08-24 18:39:24 -07:00