linux-kernel - [PATCH] rcu-tasks: Update show_rcu_tasks_trace_gp

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Message-Id: <20240326174839.487582-1-kiryushin@ancud.ru>
Date: Tue, 26 Mar 2024 20:48:39 +0300
From: Nikita Kiryushin <kiryushin@...ud.ru>
To: "Paul E. McKenney" <paulmck@...nel.org>
Cc: Nikita Kiryushin <kiryushin@...ud.ru>,
	Frederic Weisbecker <frederic@...nel.org>,
	Neeraj Upadhyay <quic_neeraju@...cinc.com>,
	Joel Fernandes <joel@...lfernandes.org>,
	Josh Triplett <josh@...htriplett.org>,
	Boqun Feng <boqun.feng@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Zqiang <qiang.zhang1211@...il.com>,
	rcu@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org
Subject: [PATCH] rcu-tasks: Update show_rcu_tasks_trace_gp_kthread buffer size

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.

Update used buffer size for maximum needed size for
current format string.

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@...ud.ru>
---
 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..13ac514489c0 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1992,7 +1992,7 @@ static int __init rcu_spawn_tasks_trace_kthread(void)
 #if !defined(CONFIG_TINY_RCU)
 void show_rcu_tasks_trace_gp_kthread(void)
 {
-	char buf[64];
+	char buf[87];
 
 	sprintf(buf, "N%lu h:%lu/%lu/%lu",
 		data_race(n_trc_holdouts),
-- 
2.34.1