[syzbot] WARNING in ip_rt_bug (2)

[syzbot <syzbot+e738404dcd14b620923c@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    a0ba26f37ea0 Merge git://git.kernel.org/pub/scm/linux/kern..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=1594a825e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=27392dd2975fd692
dashboard link: https://syzkaller.appspot.com/bug?extid=e738404dcd14b620923c
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16851c6de00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11f5d605e00000

Bisection is inconclusive: the issue happens on the oldest tested release.

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1422a825e00000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=1622a825e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=1222a825e00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e738404dcd14b620923c@syzkaller.appspotmail.com

syz-executor857 uses obsolete (PF_INET,SOCK_PACKET)
------------[ cut here ]------------
WARNING: CPU: 1 PID: 7033 at net/ipv4/route.c:1243 ip_rt_bug+0x11/0x20 net/ipv4/route.c:1242
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 7033 Comm: syz-executor857 Not tainted 5.6.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x35 kernel/panic.c:582
 report_bug+0x27b/0x2f0 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 fixup_bug arch/x86/kernel/traps.c:169 [inline]
 do_error_trap+0x12b/0x220 arch/x86/kernel/traps.c:267
 do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:ip_rt_bug+0x11/0x20 net/ipv4/route.c:1243
Code: ff ff e8 c2 d7 33 fb e9 eb fe ff ff e8 b8 d7 33 fb e9 59 ff ff ff 0f 1f 00 55 48 89 d5 e8 17 0e f7 fa 48 89 ef e8 6f 0c 8f ff <0f> 0b 31 c0 5d c3 66 0f 1f 84 00 00 00 00 00 41 54 49 89 fc e8 f6
RSP: 0018:ffffc90001937300 EFLAGS: 00010293
RAX: ffff8880a2bc2540 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff867b1711 RDI: 0000000000000286
RBP: ffff8880a31fb940 R08: 0000000000000000 R09: ffffed1015ce7074
R10: ffffed1015ce7073 R11: ffff8880ae73839b R12: ffff8880970b0e00
R13: ffff8880a31fb940 R14: ffff8880a4a71240 R15: ffff8880a31fb998
 dst_output include/net/dst.h:436 [inline]
 ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:125
 ip_send_skb+0x3e/0xe0 net/ipv4/ip_output.c:1560
 ip_push_pending_frames+0x5f/0x80 net/ipv4/ip_output.c:1580
 icmp_push_reply+0x33f/0x490 net/ipv4/icmp.c:390
 __icmp_send+0xc44/0x14a0 net/ipv4/icmp.c:740
 icmp_send include/net/icmp.h:43 [inline]
 ip_options_compile+0xad/0xf0 net/ipv4/ip_options.c:486
 ip_rcv_options net/ipv4/ip_input.c:278 [inline]
 ip_rcv_finish_core.isra.0+0x4aa/0x1ec0 net/ipv4/ip_input.c:370
 ip_rcv_finish+0x144/0x2f0 net/ipv4/ip_input.c:426
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ip_rcv+0xd0/0x3c0 net/ipv4/ip_input.c:538
 __netif_receive_skb_one_core+0xf5/0x160 net/core/dev.c:5187
 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5301
 netif_receive_skb_internal net/core/dev.c:5391 [inline]
 netif_receive_skb+0x16e/0x960 net/core/dev.c:5450
 tun_rx_batched.isra.0+0x47b/0x7d0 drivers/net/tun.c:1553
 tun_get_user+0x134a/0x3be0 drivers/net/tun.c:1997
 tun_chr_write_iter+0xb0/0x147 drivers/net/tun.c:2026
 call_write_iter include/linux/fs.h:1902 [inline]
 new_sync_write+0x49c/0x700 fs/read_write.c:483
 __vfs_write+0xc9/0x100 fs/read_write.c:496
 vfs_write+0x262/0x5c0 fs/read_write.c:558
 ksys_write+0x127/0x250 fs/read_write.c:611
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440699
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffce0515b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440699
RDX: 000000000000100c RSI: 0000000020000240 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000002c00 R09: 00007fff0000000d
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401f20
R13: 0000000000401fb0 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches