Subject: WARNING in can_rcv

From: syzbot <[email-masked]>
Date: Tue, 16 Jan 2018 09:58:02 -0800

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

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Reported-by: [email-masked]
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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..

---
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