Subject: kernel BUG at net/ipv4/ip_output.c:LINE!

From: syzbot <[email-masked]>
Date: Fri, 13 Jul 2018 01:00:02 -0700

Hello,

syzbot found the following crash on:

HEAD commit:    c25c74b7476e Merge tag 'trace-v4.18-rc3-2' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1708b92c400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=25856fac4e580aa7
dashboard link: https://syzkaller.appspot.com/bug?extid=90d5ec0c05e708f3b66d
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email-masked]

------------[ cut here ]------------
kernel BUG at net/ipv4/ip_output.c:773!
invalid opcode: 0000 [#1] SMP KASAN
CPU: 0 PID: 15085 Comm: syz-executor7 Not tainted 4.18.0-rc4+ #143
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:ip_do_fragment+0x2468/0x2ae0 net/ipv4/ip_output.c:773
Code: 8b 8d 70 fe ff ff e9 67 e8 ff ff 4c 89 ef e8 df 7a 57 fb e9 49 e9 ff  
ff 4c 89 f7 e8 d2 7a 57 fb e9 c1 e5 ff ff e8 b8 a0 19 fb <0f> 0b 4c 89 e7  
e8 be 7a 57 fb e9 85 e8 ff ff 4c 89 f7 89 8d 70 fe
RSP: 0018:ffff880195016880 EFLAGS: 00010246
RAX: 0000000000040000 RBX: ffff8801ce7be940 RCX: ffffc90002a12000
RDX: 0000000000040000 RSI: ffffffff86626ae8 RDI: 0000000000000005
RBP: ffff880195016a58 R08: ffff8801c66e8180 R09: ffffed00323180ba
R10: ffffed00323180bc R11: ffff8801918c05e3 R12: ffff8801ce7bea04
R13: 00000000fffffff2 R14: ffff8801ce7bea10 R15: dffffc0000000000
FS:  00007effc88a9700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffdeada9000 CR3: 00000001b3b5d000 CR4: 00000000001406f0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
  ip_fragment.constprop.49+0x179/0x240 net/ipv4/ip_output.c:546
  ip_finish_output+0x6e4/0xfa0 net/ipv4/ip_output.c:315
  NF_HOOK_COND include/linux/netfilter.h:276 [inline]
  ip_output+0x223/0x880 net/ipv4/ip_output.c:405
  dst_output include/net/dst.h:444 [inline]
  ip_local_out+0xc5/0x1b0 net/ipv4/ip_output.c:124
  iptunnel_xmit+0x567/0x850 net/ipv4/ip_tunnel_core.c:91
  ip_tunnel_xmit+0x1598/0x3af1 net/ipv4/ip_tunnel.c:778
  __gre_xmit+0x5e1/0x980 net/ipv4/ip_gre.c:449
  ipgre_xmit+0x3e8/0xb50 net/ipv4/ip_gre.c:701
  __netdev_start_xmit include/linux/netdevice.h:4148 [inline]
  netdev_start_xmit include/linux/netdevice.h:4157 [inline]
  xmit_one net/core/dev.c:3034 [inline]
  dev_hard_start_xmit+0x26c/0xc30 net/core/dev.c:3050
  __dev_queue_xmit+0x29ef/0x3910 net/core/dev.c:3569
  dev_queue_xmit+0x17/0x20 net/core/dev.c:3602
  __bpf_tx_skb net/core/filter.c:1952 [inline]
  __bpf_redirect_common net/core/filter.c:1990 [inline]
  __bpf_redirect+0x5b7/0xae0 net/core/filter.c:1997
  ____bpf_clone_redirect net/core/filter.c:2030 [inline]
  bpf_clone_redirect+0x2f6/0x490 net/core/filter.c:2002
  bpf_prog_bebbfe2050753572+0x12c/0x1000
Modules linked in:
Dumping ftrace buffer:
    (ftrace buffer empty)
---[ end trace 2c302777c0a564f9 ]---
RIP: 0010:ip_do_fragment+0x2468/0x2ae0 net/ipv4/ip_output.c:773
Code: 8b 8d 70 fe ff ff e9 67 e8 ff ff 4c 89 ef e8 df 7a 57 fb e9 49 e9 ff  
ff 4c 89 f7 e8 d2 7a 57 fb e9 c1 e5 ff ff e8 b8 a0 19 fb <0f> 0b 4c 89 e7  
e8 be 7a 57 fb e9 85 e8 ff ff 4c 89 f7 89 8d 70 fe
RSP: 0018:ffff880195016880 EFLAGS: 00010246
RAX: 0000000000040000 RBX: ffff8801ce7be940 RCX: ffffc90002a12000
RDX: 0000000000040000 RSI: ffffffff86626ae8 RDI: 0000000000000005
RBP: ffff880195016a58 R08: ffff8801c66e8180 R09: ffffed00323180ba
R10: ffffed00323180bc R11: ffff8801918c05e3 R12: ffff8801ce7bea04
R13: 00000000fffffff2 R14: ffff8801ce7bea10 R15: dffffc0000000000
FS:  00007effc88a9700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffdeada9000 CR3: 00000001b3b5d000 CR4: 00000000001406f0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600

---
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