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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Kuniyuki Iwashima <kuniyu@amazon.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.19 080/158] net: Fix a data-race around netdev_unregister_timeout_secs.
Date:   Mon, 29 Aug 2022 12:58:50 +0200
Message-Id: <20220829105812.403037195@linuxfoundation.org>
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From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 05e49cfc89e4f325eebbc62d24dd122e55f94c23 ]

While reading netdev_unregister_timeout_secs, it can be changed
concurrently.  Thus, we need to add READ_ONCE() to its reader.

Fixes: 5aa3afe107d9 ("net: make unregister netdev warning timeout configurable")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/core/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 19baeaf65a646..a77a979a4bf75 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10265,7 +10265,7 @@ static struct net_device *netdev_wait_allrefs_any(struct list_head *list)
 				return dev;
 
 		if (time_after(jiffies, warning_time +
-			       netdev_unregister_timeout_secs * HZ)) {
+			       READ_ONCE(netdev_unregister_timeout_secs) * HZ)) {
 			list_for_each_entry(dev, list, todo_list) {
 				pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n",
 					 dev->name, netdev_refcnt_read(dev));
-- 
2.35.1