Subject: general protection fault in skb_segment

From: syzbot <[email-masked]>
Date: Fri, 29 Dec 2017 09:58:01 -0800

Hello,

syzkaller hit the following crash on  
37759fa6d0fa9e4d6036d19ac12f555bfc0aeafd
git://git.cmpxchg.org/linux-mmots.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers

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Reported-by: [email-masked]
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kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
    (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 3154 Comm: syzkaller909359 Not tainted 4.15.0-rc4-mm1+ #49
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:skb_segment+0x667/0x2fe0 net/core/skbuff.c:3566
RSP: 0018:ffff8801c84de9b8 EFLAGS: 00010206
RAX: 000000000000000f RBX: 0000000000000000 RCX: ffffffff842c1915
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000078
RBP: ffff8801c84dec70 R08: 0000000000000020 R09: 0000000000000002
R10: ffff8801c84decf8 R11: 0000000000000000 R12: 0000000000000008
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8801d55160c0
FS:  0000000000f53880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020217f75 CR3: 00000001c86de001 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  sctp_gso_segment+0x213/0x890 net/sctp/offload.c:72
  inet_gso_segment+0x609/0x11b0 net/ipv4/af_inet.c:1288
  skb_mac_gso_segment+0x33f/0x660 net/core/dev.c:2748
  __skb_gso_segment+0x363/0x810 net/core/dev.c:2821
  skb_gso_segment include/linux/netdevice.h:3996 [inline]
  validate_xmit_skb+0x4ba/0xb20 net/core/dev.c:3074
  validate_xmit_skb_list+0xb7/0x120 net/core/dev.c:3125
  sch_direct_xmit+0x38e/0x920 net/sched/sch_generic.c:295
  qdisc_restart net/sched/sch_generic.c:366 [inline]
  __qdisc_run+0x571/0x1930 net/sched/sch_generic.c:374
  __dev_xmit_skb net/core/dev.c:3189 [inline]
  __dev_queue_xmit+0x89e/0x2200 net/core/dev.c:3489
  dev_queue_xmit+0x17/0x20 net/core/dev.c:3554
  packet_snd net/packet/af_packet.c:2943 [inline]
  packet_sendmsg+0x3ad5/0x60a0 net/packet/af_packet.c:2968
  sock_sendmsg_nosec net/socket.c:628 [inline]
  sock_sendmsg+0xca/0x110 net/socket.c:638
  sock_write_iter+0x31a/0x5d0 net/socket.c:907
  call_write_iter include/linux/fs.h:1776 [inline]
  new_sync_write fs/read_write.c:469 [inline]
  __vfs_write+0x684/0x970 fs/read_write.c:482
  vfs_write+0x189/0x510 fs/read_write.c:544
  SYSC_write fs/read_write.c:589 [inline]
  SyS_write+0xef/0x220 fs/read_write.c:581
  entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x444b69
RSP: 002b:00000000007eff78 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ffe674fbec0 RCX: 0000000000444b69
RDX: 000000000000002a RSI: 0000000020217f75 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000120080522 R09: 0000000120080522
R10: 0000000120080522 R11: 0000000000000293 R12: 0000000000402760
R13: 00000000004027f0 R14: 0000000000000000 R15: 0000000000000000
Code: 00 00 8b b5 1c fe ff ff 39 b5 30 fe ff ff 0f 8f 99 00 00 00 e8 ab 1a  
44 fd 48 8b 85 48 fe ff ff 48 8d 78 78 48 89 f8 48 c1 e8 03 <42> 0f b6 14  
28 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f
RIP: skb_segment+0x667/0x2fe0 net/core/skbuff.c:3566 RSP: ffff8801c84de9b8
---[ end trace 580392d61caec1a9 ]---

---
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