netdev - [PATCH v1 net-next 1/3] dev: Acquire netdev_rename_lock before restoring dev->name in dev_change

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Message-ID: <20250115095545.52709-2-kuniyu@amazon.com>
Date: Wed, 15 Jan 2025 18:55:43 +0900
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Simon Horman <horms@...nel.org>
CC: Kuniyuki Iwashima <kuniyu@...zon.com>, Kuniyuki Iwashima
	<kuni1840@...il.com>, <netdev@...r.kernel.org>
Subject: [PATCH v1 net-next 1/3] dev: Acquire netdev_rename_lock before restoring dev->name in dev_change_name().

The cited commit forgot to add netdev_rename_lock in one of the
error paths in dev_change_name().

Let's hold netdev_rename_lock before restoring the old dev->name.

Fixes: 0840556e5a3a ("net: Protect dev->name by seqlock.")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
 net/core/dev.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/core/dev.c b/net/core/dev.c
index fda4e1039bf0..0237687d4a41 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1277,7 +1277,9 @@ int dev_change_name(struct net_device *dev, const char *newname)
 rollback:
 	ret = device_rename(&dev->dev, dev->name);
 	if (ret) {
+		write_seqlock_bh(&netdev_rename_lock);
 		memcpy(dev->name, oldname, IFNAMSIZ);
+		write_sequnlock_bh(&netdev_rename_lock);
 		WRITE_ONCE(dev->name_assign_type, old_assign_type);
 		up_write(&devnet_rename_sem);
 		return ret;
-- 
2.39.5 (Apple Git-154)