On 12/21/2017 04:13 PM, Tommi Rantala wrote:
> Calling tipc_mon_delete() before the monitor has been created will oops.
> This can happen in tipc_enable_bearer() error path if tipc_disc_create()
> fails.
> 
> [   48.589074] BUG: unable to handle kernel paging request at 0000000000001008
> [   48.590266] IP: tipc_mon_delete+0xea/0x270 [tipc]
> [   48.591223] PGD 1e60c5067 P4D 1e60c5067 PUD 1eb0cf067 PMD 0
> [   48.592230] Oops: 0000 [#1] SMP KASAN
> [   48.595610] CPU: 5 PID: 1199 Comm: tipc Tainted: G    B            
> 4.15.0-rc4-pc64-dirty #5
> [   48.597176] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
> 1.10.2-2.fc27 04/01/2014
> [   48.598489] RIP: 0010:tipc_mon_delete+0xea/0x270 [tipc]
> [   48.599347] RSP: 0018:ffff8801d827f668 EFLAGS: 00010282
> [   48.600705] RAX: ffff8801ee813f00 RBX: 0000000000000204 RCX: 
> 0000000000000000
> [   48.602183] RDX: 1ffffffff1de6a75 RSI: 0000000000000297 RDI: 
> 0000000000000297
> [   48.604373] RBP: 0000000000000000 R08: 0000000000000000 R09: 
> fffffbfff1dd1533
> [   48.605607] R10: ffffffff8eafbb05 R11: fffffbfff1dd1534 R12: 
> 0000000000000050
> [   48.607082] R13: dead000000000200 R14: ffffffff8e73f310 R15: 
> 0000000000001020
> [   48.608228] FS:  00007fc686484800(0000) GS:ffff8801f5540000(0000) 
> knlGS:0000000000000000
> [   48.610189] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   48.611459] CR2: 0000000000001008 CR3: 00000001dda70002 CR4: 
> 00000000003606e0
> [   48.612759] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 
> 0000000000000000
> [   48.613831] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 
> 0000000000000400
> [   48.615038] Call Trace:
> [   48.615635]  tipc_enable_bearer+0x415/0x5e0 [tipc]
> [   48.620623]  tipc_nl_bearer_enable+0x1ab/0x200 [tipc]
> [   48.625118]  genl_family_rcv_msg+0x36b/0x570
> [   48.631233]  genl_rcv_msg+0x5a/0xa0
> [   48.631867]  netlink_rcv_skb+0x1cc/0x220
> [   48.636373]  genl_rcv+0x24/0x40
> [   48.637306]  netlink_unicast+0x29c/0x350
> [   48.639664]  netlink_sendmsg+0x439/0x590
> [   48.642014]  SYSC_sendto+0x199/0x250
> [   48.649912]  do_syscall_64+0xfd/0x2c0
> [   48.650651]  entry_SYSCALL64_slow_path+0x25/0x25
> [   48.651843] RIP: 0033:0x7fc6859848e3
> [   48.652539] RSP: 002b:00007ffd25dff938 EFLAGS: 00000246 ORIG_RAX: 
> 000000000000002c
> [   48.654003] RAX: ffffffffffffffda RBX: 00007ffd25dff990 RCX: 
> 00007fc6859848e3
> [   48.655303] RDX: 0000000000000054 RSI: 00007ffd25dff990 RDI: 
> 0000000000000003
> [   48.656512] RBP: 00007ffd25dff980 R08: 00007fc685c35fc0 R09: 
> 000000000000000c
> [   48.657697] R10: 0000000000000000 R11: 0000000000000246 R12: 
> 0000000000d13010
> [   48.658840] R13: 00007ffd25e009c0 R14: 0000000000000000 R15: 
> 0000000000000000
> [   48.662972] RIP: tipc_mon_delete+0xea/0x270 [tipc] RSP: ffff8801d827f668
> [   48.664073] CR2: 0000000000001008
> [   48.664576] ---[ end trace e811818d54d5ce88 ]---
> 
> Signed-off-by: Tommi Rantala <[email protected]>

Acked-by: Ying Xue <[email protected]>

> ---
>  net/tipc/monitor.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/net/tipc/monitor.c b/net/tipc/monitor.c
> index 8e884ed06d4b..32dc33a94bc7 100644
> --- a/net/tipc/monitor.c
> +++ b/net/tipc/monitor.c
> @@ -642,9 +642,13 @@ void tipc_mon_delete(struct net *net, int bearer_id)
>  {
>       struct tipc_net *tn = tipc_net(net);
>       struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
> -     struct tipc_peer *self = get_self(net, bearer_id);
> +     struct tipc_peer *self;
>       struct tipc_peer *peer, *tmp;
>  
> +     if (!mon)
> +             return;
> +
> +     self = get_self(net, bearer_id);
>       write_lock_bh(&mon->lock);
>       tn->monitors[bearer_id] = NULL;
>       list_for_each_entry_safe(peer, tmp, &self->list, list) {
> 

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