linux-kernel - [PATCH AUTOSEL 5.4 32/32] drivers: net: hamradio: Fix suspicious RCU usage warning in bpqether.c

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Message-Id: <20200522145044.434677-32-sashal@kernel.org>
Date:   Fri, 22 May 2020 10:50:44 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>,
        syzbot+bb82cafc737c002d11ca@...kaller.appspotmail.com,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 32/32] drivers: net: hamradio: Fix suspicious RCU usage warning in bpqether.c

From: Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>

[ Upstream commit 95f59bf88bb75281cc626e283ecefdd5d5641427 ]

This patch fixes the following warning:
=============================
WARNING: suspicious RCU usage
5.7.0-rc5-next-20200514-syzkaller #0 Not tainted
-----------------------------
drivers/net/hamradio/bpqether.c:149 RCU-list traversed in non-reader section!!

Since rtnl lock is held, pass this cond in list_for_each_entry_rcu().

Reported-by: syzbot+bb82cafc737c002d11ca@...kaller.appspotmail.com
Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/hamradio/bpqether.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/hamradio/bpqether.c b/drivers/net/hamradio/bpqether.c
index fbea6f232819..e2ad3c2e8df5 100644
--- a/drivers/net/hamradio/bpqether.c
+++ b/drivers/net/hamradio/bpqether.c
@@ -127,7 +127,8 @@ static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev)
 {
 	struct bpqdev *bpq;
 
-	list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list) {
+	list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list,
+				lockdep_rtnl_is_held()) {
 		if (bpq->ethdev == dev)
 			return bpq->axdev;
 	}
-- 
2.25.1