RE: [PATCH] tipc: fix NULL pointer dereference in shutdown()

[Jon Maloy]

Sorry, I just came back from vacation today.

Acked-by: Jon Maloy <jon.maloy@xxxxxxxxxxxx>


> -----Original Message-----
> From: Vegard Nossum [mailto:vegard.nossum@xxxxxxxxxx]
> Sent: Friday, 12 August, 2016 10:38
> To: Ying Xue <ying.xue@xxxxxxxxxxxxx>; Jon Maloy <jon.maloy@xxxxxxxxxxxx>;
> David S. Miller <davem@xxxxxxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx; Michael Kerrisk <mtk.manpages@xxxxxxxxx>;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] tipc: fix NULL pointer dereference in shutdown()
> 
> Hi,
> 
> I didn't see this patch go in yet. Jon Maloy, ping?
> 
> Should this go through somebody else?
> 
> 
> Vegard
> 
> On 07/23/2016 11:49 AM, Xue, Ying wrote:
> > Acked-by: Ying Xue <ying.xue@xxxxxxxxxxxxx>
> >
> > -----Original Message-----
> > From: Vegard Nossum [mailto:vegard.nossum@xxxxxxxxxx]
> > Sent: Saturday, July 23, 2016 2:15 PM
> > To: Jon Maloy; Xue, Ying
> > Cc: netdev@xxxxxxxxxxxxxxx; David S. Miller; Michael Kerrisk; linux-
> kernel@xxxxxxxxxxxxxxx; Vegard Nossum; stable@xxxxxxxxxxxxxxx
> > Subject: [PATCH] tipc: fix NULL pointer dereference in shutdown()
> >
> > tipc_msg_create() can return a NULL skb and if so, we shouldn't try to call
> tipc_node_xmit_skb() on it.
> >
> >      general protection fault: 0000 [#1] PREEMPT SMP KASAN
> >      CPU: 3 PID: 30298 Comm: trinity-c0 Not tainted 4.7.0-rc7+ #19
> >      Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-
> 1.8.2-1ubuntu1 04/01/2014
> >      task: ffff8800baf09980 ti: ffff8800595b8000 task.ti: ffff8800595b8000
> >      RIP: 0010:[<ffffffff830bb46b>]  [<ffffffff830bb46b>]
> tipc_node_xmit_skb+0x6b/0x140
> >      RSP: 0018:ffff8800595bfce8  EFLAGS: 00010246
> >      RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000003023b0e0
> >      RDX: 0000000000000000 RSI: dffffc0000000000 RDI: ffffffff83d12580
> >      RBP: ffff8800595bfd78 R08: ffffed000b2b7f32 R09: 0000000000000000
> >      R10: fffffbfff0759725 R11: 0000000000000000 R12: 1ffff1000b2b7f9f
> >      R13: ffff8800595bfd58 R14: ffffffff83d12580 R15: dffffc0000000000
> >      FS:  00007fcdde242700(0000) GS:ffff88011af80000(0000)
> knlGS:0000000000000000
> >      CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >      CR2: 00007fcddde1db10 CR3: 000000006874b000 CR4: 00000000000006e0
> >      DR0: 00007fcdde248000 DR1: 00007fcddd73d000 DR2: 00007fcdde248000
> >      DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000090602
> >      Stack:
> >       0000000000000018 0000000000000018 0000000041b58ab3 ffffffff83954208
> >       ffffffff830bb400 ffff8800595bfd30 ffffffff8309d767 0000000000000018
> >       0000000000000018 ffff8800595bfd78 ffffffff8309da1a 00000000810ee611
> >      Call Trace:
> >       [<ffffffff830c84a3>] tipc_shutdown+0x553/0x880
> >       [<ffffffff825b4a3b>] SyS_shutdown+0x14b/0x170
> >       [<ffffffff8100334c>] do_syscall_64+0x19c/0x410
> >       [<ffffffff83295ca5>] entry_SYSCALL64_slow_path+0x25/0x25
> >      Code: 90 00 b4 0b 83 c7 00 f1 f1 f1 f1 4c 8d 6d e0 c7 40 04 00 00 00 f4 c7 40 08 f3
> f3 f3 f3 48 89 d8 48 c1 e8 03 c7 45 b4 00 00 00 00 <80> 3c 30 00 75 78 48 8d 7b 08 49
> 8d 75 c0 48 b8 00 00 00 00 00
> >      RIP  [<ffffffff830bb46b>] tipc_node_xmit_skb+0x6b/0x140
> >       RSP <ffff8800595bfce8>
> >      ---[ end trace 57b0484e351e71f1 ]---
> >
> > I feel like we should maybe return -ENOMEM or -ENOBUFS, but I'm not sure
> userspace is equipped to handle that. Anyway, this is better than a GPF and looks
> somewhat consistent with other tipc_msg_create() callers.
> >
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
> > ---
> >   net/tipc/socket.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/tipc/socket.c b/net/tipc/socket.c index c49b8df..f9f5f3c 100644
> > --- a/net/tipc/socket.c
> > +++ b/net/tipc/socket.c
> > @@ -2180,7 +2180,8 @@ restart:
> >   					      TIPC_CONN_MSG, SHORT_H_SIZE,
> >   					      0, dnode, onode, dport, oport,
> >   					      TIPC_CONN_SHUTDOWN);
> > -			tipc_node_xmit_skb(net, skb, dnode, tsk->portid);
> > +			if (skb)
> > +				tipc_node_xmit_skb(net, skb, dnode, tsk-
> >portid);
> >   		}
> >   		tsk->connected = 0;
> >   		sock->state = SS_DISCONNECTING;
> > --
> > 1.9.1
> >