Subject: kernel BUG at ./include/linux/skbuff.h:LINE!

From: syzbot <[email-masked]>
Date: Thu, 04 Jan 2018 07:58:01 -0800

Hello,

syzkaller hit the following crash on  
ead68f216110170ec729e2c4dec0aad6d38259d7
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email-masked]
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If you forward the report, please keep this part and the footer.

------------[ cut here ]------------
kernel BUG at ./include/linux/skbuff.h:2068!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
    (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 3145 Comm: syzkaller456978 Not tainted 4.15.0-rc4+ #234
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:__skb_pull include/linux/skbuff.h:2068 [inline]
RIP: 0010:skb_pull_inline include/linux/skbuff.h:2074 [inline]
RIP: 0010:skb_pull+0xd5/0xf0 net/core/skbuff.c:1731
RSP: 0018:ffff8801c921f270 EFLAGS: 00010293
RAX: ffff8801ca472480 RBX: ffff8801c81123c0 RCX: ffffffff841bb0b5
RDX: 0000000000000000 RSI: 0000000000000028 RDI: ffff8801c811243c
RBP: ffff8801c921f288 R08: 1ffff10039243db7 R09: 0000000000000002
R10: ffff8801c921f278 R11: 0000000000000000 R12: 0000000000000028
R13: 0000000000000010 R14: dffffc0000000000 R15: 0000000000000000
FS:  0000000001ca4880(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002084c000 CR3: 00000001ca73c003 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  esp6_gro_receive+0xb4/0xbe0 net/ipv6/esp6_offload.c:63
  call_gro_receive include/linux/netdevice.h:2200 [inline]
  ipv6_gro_receive+0x83e/0x13c0 net/ipv6/ip6_offload.c:253
  dev_gro_receive+0xd2c/0x2120 net/core/dev.c:4857
  napi_gro_frags+0x377/0xad0 net/core/dev.c:5113
  tun_get_user+0x25f5/0x36d0 drivers/net/tun.c:1757
  tun_chr_write_iter+0xb9/0x160 drivers/net/tun.c:1800
  call_write_iter include/linux/fs.h:1772 [inline]
  do_iter_readv_writev+0x525/0x7f0 fs/read_write.c:653
  do_iter_write+0x154/0x540 fs/read_write.c:932
  vfs_writev+0x18a/0x340 fs/read_write.c:977
  do_writev+0xfc/0x2a0 fs/read_write.c:1012
  SYSC_writev fs/read_write.c:1085 [inline]
  SyS_writev+0x27/0x30 fs/read_write.c:1082
  entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x444e50
RSP: 002b:00007fff5a4f08d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000444e50
RDX: 0000000000000002 RSI: 00007fff5a4f08e0 RDI: 0000000000000003
RBP: 00000000006d0018 R08: 000000002084c046 R09: 0000000000000046
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000402390
R13: 0000000000402420 R14: 0000000000000000 R15: 0000000000000000
Code: a3 d0 00 00 00 e8 fc 38 54 fd 4c 89 e0 5b 41 5c 41 5d 5d c3 45 31 e4  
e8 ea 38 54 fd 4c 89 e0 5b 41 5c 41 5d 5d c3 e8 db 38 54 fd <0f> 0b e8 d4  
af 8a fd eb 9a e8 cd af 8a fd e9 51 ff ff ff e8 e3
RIP: __skb_pull include/linux/skbuff.h:2068 [inline] RSP: ffff8801c921f270
RIP: skb_pull_inline include/linux/skbuff.h:2074 [inline] RSP:  
ffff8801c921f270
RIP: skb_pull+0xd5/0xf0 net/core/skbuff.c:1731 RSP: ffff8801c921f270
---[ end trace c8c7c2ebe84a87dd ]---

---
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