diff options
| author | Nikita Kiryushin <kiryushin@ancud.ru> | 2024-04-01 22:43:15 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-05-30 09:44:06 +0200 |
| commit | 4c3e2ef4d8ddd313c8ce3ac30505940bea8d6257 (patch) | |
| tree | 0e3400a8b3e01a57a977603828a1f2a4b65d77c3 | |
| parent | 1a240e138071b25944ded0f5b3e357aa99fabcb7 (diff) | |
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>
| -rw-r--r-- | kernel/rcu/tree_stall.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 5d666428546b..b5ec62b2d850 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -504,7 +504,8 @@ static void print_cpu_stall_info(int cpu) rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu)); rcuc_starved = rcu_is_rcuc_kthread_starving(rdp, &j); if (rcuc_starved) - sprintf(buf, " rcuc=%ld jiffies(starved)", j); + // Print signed value, as negative values indicate a probable bug. + snprintf(buf, sizeof(buf), " rcuc=%ld jiffies(starved)", j); pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%04x/%ld/%#lx softirq=%u/%u fqs=%ld%s%s\n", cpu, "O."[!!cpu_online(cpu)], |