Subject: WARNING in skb_warn_bad_offload

From: syzbot <[email-masked]>
Date: Wed, 01 Nov 2017 11:48:47 -0700

Hello,

syzkaller hit the following crash on  
720bbe532b7c8f5613b48dea627fc58ed9ace707
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

------------[ cut here ]------------
WARNING: CPU: 0 PID: 2986 at net/core/dev.c:2585  
skb_warn_bad_offload+0x2a9/0x380 net/core/dev.c:2580
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 2986 Comm: syzkaller546001 Not tainted 4.13.0-mm1+ #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:16 [inline]
  dump_stack+0x194/0x257 lib/dump_stack.c:52
  panic+0x1e4/0x417 kernel/panic.c:181
  __warn+0x1c4/0x1d9 kernel/panic.c:542
  report_bug+0x211/0x2d0 lib/bug.c:183
  fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:178
  do_trap_no_signal arch/x86/kernel/traps.c:212 [inline]
  do_trap+0x260/0x390 arch/x86/kernel/traps.c:261
  do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:298
  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:311
  invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:905
RIP: 0010:skb_warn_bad_offload+0x2a9/0x380 net/core/dev.c:2580
RSP: 0018:ffff8801ce73f0a0 EFLAGS: 00010282
RAX: 000000000000006f RBX: ffff8801cd84cde0 RCX: 0000000000000000
RDX: 000000000000006f RSI: 1ffff10039ce7dd4 RDI: ffffed0039ce7e08
RBP: ffff8801ce73f0f8 R08: ffff8801ce73e790 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ce7802c0
R13: 0000000000000000 R14: ffff8801ce7802c0 R15: 0000000000002111
  __skb_gso_segment+0x607/0x7f0 net/core/dev.c:2791
  skb_gso_segment include/linux/netdevice.h:3951 [inline]
  validate_xmit_skb+0x4ba/0xb20 net/core/dev.c:3041
  validate_xmit_skb_list+0xb7/0x120 net/core/dev.c:3092
  sch_direct_xmit+0x3b6/0x6d0 net/sched/sch_generic.c:181
  __dev_xmit_skb net/core/dev.c:3173 [inline]
  __dev_queue_xmit+0x15fe/0x1e40 net/core/dev.c:3440
  dev_queue_xmit+0x17/0x20 net/core/dev.c:3505
  packet_snd net/packet/af_packet.c:2950 [inline]
  packet_sendmsg+0x3bbf/0x6030 net/packet/af_packet.c:2975
  sock_sendmsg_nosec net/socket.c:633 [inline]
  sock_sendmsg+0xca/0x110 net/socket.c:643
  ___sys_sendmsg+0x75b/0x8a0 net/socket.c:2049
  __sys_sendmsg+0xe5/0x210 net/socket.c:2083
  SYSC_sendmsg net/socket.c:2094 [inline]
  SyS_sendmsg+0x2d/0x50 net/socket.c:2090
  entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x445489
RSP: 002b:00000000007efe68 EFLAGS: 00000217 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000445489
RDX: 0000000000004010 RSI: 00000000207fcfc8 RDI: 0000000000000004
RBP: 0000000000000082 R08: 000000000000cdf3 R09: 000000000000cdf3
R10: 0000000000000004 R11: 0000000000000217 R12: 0000000000402ae0
R13: 0000000000402b70 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..

---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to [email-masked].
Please credit me with: Reported-by: syzbot <[email-masked]>

syzbot will keep track of this bug report.
Once a fix for this bug is committed, please reply to this email with:
#syz fix: exact-commit-title
To mark this as a duplicate of another syzbot report, please reply with:
#syz dup: exact-subject-of-another-report
If it's a one-off invalid bug report, please reply with:
#syz invalid
Note: if the crash happens again, it will cause creation of a new bug  
report.
Note: all commands must start from beginning of the line.