net: Don't warn on ENOMEM in __dev_change_net_namespace

syzkaller found a WARN in __dev_change_net_namespace when
device_rename() returns ENOMEM:

------------[ cut here ]------------
WARNING: CPU: 1 PID: 6395 at net/core/dev.c:11430 __dev_change_net_namespace+0xba7/0xbf0
Modules linked in:
CPU: 1 PID: 6395 Comm: syz-executor.1 Not tainted 6.9.0-g4eea1d874bbf kernel-patches#66
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014
RIP: 0010:__dev_change_net_namespace+0xba7/0xbf0 net/core/dev.c:11430
Code: 05 d6 72 34 01 01 48 c7 c7 ea e8 c4 82 48 c7 c6 21 d2 cb 82 ba bf 07 00 00 e8 25 cc 39 ff 0f 0b e9 5b f8 ff ff e8 c9 b3 4f ff <0f> 0b e9 ca fc ff ff e8 bd b3 4f ff 0f 0b e9 5f fe ff ff e8 b1 b3
RSP: 0018:ffffc90000d1f410 EFLAGS: 00010293
RAX: ffffffff81d1d487 RBX: ffff8881213b5000 RCX: ffff888115f9adc0
RDX: 0000000000000000 RSI: 00000000fffffff4 RDI: 0000000000000000
RBP: ffffc90000d1f4e0 R08: ffffffff81d1d14a R09: 205d393032343136
R10: 3e4b5341542f3c20 R11: ffffffff81a40d20 R12: ffff88811f57af40
R13: 0000000000000000 R14: 00000000fffffff4 R15: ffff8881213b5000
FS:  00007fc93618e640(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000468d90 CR3: 0000000126252003 CR4: 0000000000170ef0
Call Trace:
 <TASK>
 do_setlink+0x154/0x1c70 net/core/rtnetlink.c:2805
 __rtnl_newlink net/core/rtnetlink.c:3696 [inline]
 rtnl_newlink+0xe60/0x1210 net/core/rtnetlink.c:3743
 rtnetlink_rcv_msg+0x689/0x720 net/core/rtnetlink.c:6595
 netlink_rcv_skb+0xea/0x1c0 net/netlink/af_netlink.c:2564
 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
 netlink_unicast+0x430/0x500 net/netlink/af_netlink.c:1361
 netlink_sendmsg+0x43d/0x540 net/netlink/af_netlink.c:1905
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0xa4/0xd0 net/socket.c:745
 ____sys_sendmsg+0x22a/0x320 net/socket.c:2585
 ___sys_sendmsg+0x143/0x190 net/socket.c:2639
 __sys_sendmsg net/socket.c:2668 [inline]
 __do_sys_sendmsg net/socket.c:2677 [inline]
 __se_sys_sendmsg net/socket.c:2675 [inline]
 __x64_sys_sendmsg+0xd8/0x150 net/socket.c:2675
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x54/0xf0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fc936e686a9

The WARN is there because device_rename() is indeed not meant to
fail in __dev_change_net_namespace(), except for the case where
it can't allocated memory.

So, let's special-case the scenario where err == ENOMEM to silence the
warning.

AFAICS, this has been there since the initial implementation.

Cc: Eric W. Biederman <[email protected]>
Fixes: ce286d3 ("[NET]: Implement network device movement between namespaces")
Signed-off-by: Christoph Paasch <[email protected]>
Signed-off-by: NipaLocal <nipa@local>

net/core/dev.c

@@ -11428,7 +11428,7 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net,
 	dev_set_uevent_suppress(&dev->dev, 1);
 	err = device_rename(&dev->dev, dev->name);
 	dev_set_uevent_suppress(&dev->dev, 0);
-	WARN_ON(err);
+	WARN_ON(err && err != -ENOMEM);
 
 	/* Send a netdev-add uevent to the new namespace */
 	kobject_uevent(&dev->dev.kobj, KOBJ_ADD);