Hello,

syzkaller hit the following crash on  
a8750ddca918032d6349adbf9a4b6555e7db20da
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: syzbot+4386709c0c1284dca827@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

device eql entered promiscuous mode
------------[ cut here ]------------
PF_CAN: dropped non conform CAN skbuf: dev type 65534, len 42, datalen 0
WARNING: CPU: 0 PID: 3650 at net/can/af_can.c:729 can_rcv+0x1c5/0x200  
net/can/af_can.c:724
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 3650 Comm: syzkaller340557 Not tainted 4.15.0-rc8+ #263
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x194/0x257 lib/dump_stack.c:53
  panic+0x1e4/0x41c kernel/panic.c:183
  __warn+0x1dc/0x200 kernel/panic.c:547
  report_bug+0x211/0x2d0 lib/bug.c:184
  fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178
  fixup_bug arch/x86/kernel/traps.c:247 [inline]
  do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
  invalid_op+0x22/0x40 arch/x86/entry/entry_64.S:1085
RIP: 0010:can_rcv+0x1c5/0x200 net/can/af_can.c:724
RSP: 0018:ffff8801bbe57068 EFLAGS: 00010286
RAX: dffffc0000000008 RBX: ffff8801d947ae40 RCX: ffffffff8159dade
RDX: 0000000000000000 RSI: 1ffff100377cadc8 RDI: ffff8801bbe56d70
RBP: ffff8801bbe57090 R08: 0000000000000000 R09: 0000000000000000
R10: ffff8801bbe575b0 R11: 0000000000000000 R12: ffff8801d99f8380
R13: ffff8801d9a3d040 R14: 000000000000fffe R15: ffffffff8704d800
  __netif_receive_skb_core+0x1a41/0x3460 net/core/dev.c:4473
  __netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4538
  netif_receive_skb_internal+0x10b/0x670 net/core/dev.c:4611
  netif_receive_skb+0xae/0x390 net/core/dev.c:4635
  tun_rx_batched.isra.50+0x5ee/0x870 drivers/net/tun.c:1378
  tun_get_user+0x24ac/0x3710 drivers/net/tun.c:1774
  tun_chr_write_iter+0xb9/0x160 drivers/net/tun.c:1800
  call_write_iter include/linux/fs.h:1772 [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+0x29/0xa0
RIP: 0033:0x4445d9
RSP: 002b:00007fffbeafb128 EFLAGS: 00000217 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: ffffffffffffffff RCX: 00000000004445d9
RDX: 000000000000002e RSI: 0000000020b61fd2 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000217 R12: 00000000006c7165
R13: 0000000000401fb0 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 syzkaller@googlegroups.com.

syzbot will keep track of this bug report.
If you forgot to add the Reported-by tag, once the fix for this bug is  
merged
into any tree, please reply to this email with:
#syz fix: exact-commit-title
If you want to test a patch for this bug, please reply with:
#syz test: git://repo/address.git branch
and provide the patch inline or as an attachment.
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 in the email body.