From: YueHaibing yuehaibing@huawei.com
[ Upstream commit 638a3a1e349ddf5b82f222ff5cb3b4f266e7c278 ]
BUG: unable to handle kernel NULL pointer dereference at 0000000000000128 PGD 0 P4D 0 Oops: 0000 [#1 CPU: 0 PID: 5697 Comm: modprobe Tainted: G W 5.1.0-rc7+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 RIP: 0010:__lock_acquire+0x53/0x10b0 Code: 8b 1c 25 40 5e 01 00 4c 8b 6d 10 45 85 e4 0f 84 bd 06 00 00 44 8b 1d 7c d2 09 02 49 89 fe 41 89 d2 45 85 db 0f 84 47 02 00 00 <48> 81 3f a0 05 70 83 b8 00 00 00 00 44 0f 44 c0 83 fe 01 0f 86 3a RSP: 0018:ffffc90001c07a28 EFLAGS: 00010002 RAX: 0000000000000000 RBX: ffff88822f038440 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000128 RBP: ffffc90001c07a88 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000001 R13: 0000000000000000 R14: 0000000000000128 R15: 0000000000000000 FS: 00007fead0811540(0000) GS:ffff888237a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000128 CR3: 00000002310da000 CR4: 00000000000006f0 Call Trace: ? __lock_acquire+0x24e/0x10b0 lock_acquire+0xdf/0x230 ? flush_workqueue+0x71/0x530 flush_workqueue+0x97/0x530 ? flush_workqueue+0x71/0x530 l2tp_exit_net+0x170/0x2b0 [l2tp_core ? l2tp_exit_net+0x93/0x2b0 [l2tp_core ops_exit_list.isra.6+0x36/0x60 unregister_pernet_operations+0xb8/0x110 unregister_pernet_device+0x25/0x40 l2tp_init+0x55/0x1000 [l2tp_core ? 0xffffffffa018d000 do_one_initcall+0x6c/0x3cc ? do_init_module+0x22/0x1f1 ? rcu_read_lock_sched_held+0x97/0xb0 ? kmem_cache_alloc_trace+0x325/0x3b0 do_init_module+0x5b/0x1f1 load_module+0x1db1/0x2690 ? m_show+0x1d0/0x1d0 __do_sys_finit_module+0xc5/0xd0 __x64_sys_finit_module+0x15/0x20 do_syscall_64+0x6b/0x1d0 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fead031a839 Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 1f f6 2c 00 f7 d8 64 89 01 48 RSP: 002b:00007ffe8d9acca8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 RAX: ffffffffffffffda RBX: 0000560078398b80 RCX: 00007fead031a839 RDX: 0000000000000000 RSI: 000056007659dc2e RDI: 0000000000000003 RBP: 000056007659dc2e R08: 0000000000000000 R09: 0000560078398b80 R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000 R13: 00005600783a04a0 R14: 0000000000040000 R15: 0000560078398b80 Modules linked in: l2tp_core(+) e1000 ip_tables ipv6 [last unloaded: l2tp_core CR2: 0000000000000128 ---[ end trace 8322b2b8bf83f8e1
If alloc_workqueue fails in l2tp_init, l2tp_net_ops is unregistered on failure path. Then l2tp_exit_net is called which will flush NULL workqueue, this patch add a NULL check to fix it.
Fixes: 67e04c29ec0d ("l2tp: unregister l2tp_net_ops on failure path") Signed-off-by: YueHaibing yuehaibing@huawei.com Acked-by: Guillaume Nault gnault@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/l2tp/l2tp_core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 52b5a2797c0c..e4dec03a19fe 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1735,7 +1735,8 @@ static __net_exit void l2tp_exit_net(struct net *net) } rcu_read_unlock_bh();
- flush_workqueue(l2tp_wq); + if (l2tp_wq) + flush_workqueue(l2tp_wq); rcu_barrier();
for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)