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Subject[PATCH 4.4 013/101] net: 8021q: Fix one possible panic caused by BUG_ON in free_netdev
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Gao Feng <gfree.wind@vip.163.com>


[ Upstream commit 9745e362add89432d2c951272a99b0a5fe4348a9 ]

The register_vlan_device would invoke free_netdev directly, when
register_vlan_dev failed. It would trigger the BUG_ON in free_netdev
if the dev was already registered. In this case, the netdev would be
freed in netdev_run_todo later.

So add one condition check now. Only when dev is not registered, then
free it directly.

The following is the part coredump when netdev_upper_dev_link failed
in register_vlan_dev. I removed the lines which are too long.

[ 411.237457] ------------[ cut here ]------------
[ 411.237458] kernel BUG at net/core/dev.c:7998!
[ 411.237484] invalid opcode: 0000 [#1] SMP
[ 411.237705] [last unloaded: 8021q]
[ 411.237718] CPU: 1 PID: 12845 Comm: vconfig Tainted: G E 4.12.0-rc5+ #6
[ 411.237737] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/02/2015
[ 411.237764] task: ffff9cbeb6685580 task.stack: ffffa7d2807d8000
[ 411.237782] RIP: 0010:free_netdev+0x116/0x120
[ 411.237794] RSP: 0018:ffffa7d2807dbdb0 EFLAGS: 00010297
[ 411.237808] RAX: 0000000000000002 RBX: ffff9cbeb6ba8fd8 RCX: 0000000000001878
[ 411.237826] RDX: 0000000000000001 RSI: 0000000000000282 RDI: 0000000000000000
[ 411.237844] RBP: ffffa7d2807dbdc8 R08: 0002986100029841 R09: 0002982100029801
[ 411.237861] R10: 0004000100029980 R11: 0004000100029980 R12: ffff9cbeb6ba9000
[ 411.238761] R13: ffff9cbeb6ba9060 R14: ffff9cbe60f1a000 R15: ffff9cbeb6ba9000
[ 411.239518] FS: 00007fb690d81700(0000) GS:ffff9cbebb640000(0000) knlGS:0000000000000000
[ 411.239949] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 411.240454] CR2: 00007f7115624000 CR3: 0000000077cdf000 CR4: 00000000003406e0
[ 411.240936] Call Trace:
[ 411.241462] vlan_ioctl_handler+0x3f1/0x400 [8021q]
[ 411.241910] sock_ioctl+0x18b/0x2c0
[ 411.242394] do_vfs_ioctl+0xa1/0x5d0
[ 411.242853] ? sock_alloc_file+0xa6/0x130
[ 411.243465] SyS_ioctl+0x79/0x90
[ 411.243900] entry_SYSCALL_64_fastpath+0x1e/0xa9
[ 411.244425] RIP: 0033:0x7fb69089a357
[ 411.244863] RSP: 002b:00007ffcd04e0fc8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
[ 411.245445] RAX: ffffffffffffffda RBX: 00007ffcd04e2884 RCX: 00007fb69089a357
[ 411.245903] RDX: 00007ffcd04e0fd0 RSI: 0000000000008983 RDI: 0000000000000003
[ 411.246527] RBP: 00007ffcd04e0fd0 R08: 0000000000000000 R09: 1999999999999999
[ 411.246976] R10: 000000000000053f R11: 0000000000000202 R12: 0000000000000004
[ 411.247414] R13: 00007ffcd04e1128 R14: 00007ffcd04e2888 R15: 0000000000000001
[ 411.249129] RIP: free_netdev+0x116/0x120 RSP: ffffa7d2807dbdb0

Signed-off-by: Gao Feng <gfree.wind@vip.163.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/8021q/vlan.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -278,7 +278,8 @@ static int register_vlan_device(struct n
return 0;

out_free_newdev:
- free_netdev(new_dev);
+ if (new_dev->reg_state == NETREG_UNINITIALIZED)
+ free_netdev(new_dev);
return err;
}


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