Subject: kernel BUG at net/ipv6/route.c:LINE! (2)

From: syzbot <[email-masked]>
Date: Mon, 07 Jan 2019 02:02:03 -0800

Hello,

syzbot found the following crash on:

HEAD commit:    b71acb0e3721 Merge branch 'linus' of git://git.kernel.org/..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11d5f9bb400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b03c5892bb940c76
dashboard link: https://syzkaller.appspot.com/bug?extid=be0943c590bb47aefb9e
compiler:       gcc (GCC) 9.0.0 20181231 (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/ipv6/route.c:1260!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
kobject: 'loop3' (000000002b424f37): kobject_uevent_env
CPU: 0 PID: 11990 Comm: syz-executor0 Not tainted 4.20.0+ #3
kobject: 'loop3' (000000002b424f37): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:rt6_make_pcpu_route net/ipv6/route.c:1260 [inline]
RIP: 0010:ip6_pol_route+0x82f/0x1490 net/ipv6/route.c:1893
Code: 48 03 1c c5 60 70 55 89 be 08 00 00 00 48 89 df e8 66 de f1 fa 31 c0  
f0 4c 0f b1 3b 48 85 c0 0f 84 b3 fb ff ff e8 d1 c0 ae fa <0f> 0b e8 ca c0  
ae fa e8 c5 8b 99 fa 31 ff 89 c6 88 85 c8 fe ff ff
RSP: 0018:ffff888092cb6dd0 EFLAGS: 00010212
netlink: 188 bytes leftover after parsing attributes in process  
`syz-executor3'.
RAX: 0000000000040000 RBX: ffffe8ffffc2e0b0 RCX: ffffc900061fb000
RDX: 0000000000000a5c RSI: ffffffff86d2e53f RDI: ffffe8ffffc2e0b0
RBP: ffff888092cb6f18 R08: 1ffffd1ffff85c16 R09: fffff91ffff85c17
R10: fffff91ffff85c16 R11: ffffe8ffffc2e0b7 R12: ffff88809b57e1c0
R13: 0000000000000001 R14: ffff888092cb6ef0 R15: ffff888088b0c640
FS:  00007fb67723e700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f817add4518 CR3: 0000000097a79000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
netlink: 188 bytes leftover after parsing attributes in process  
`syz-executor3'.
Call Trace:
kobject: 'loop3' (000000002b424f37): kobject_uevent_env
  ip6_pol_route_input+0x65/0x80 net/ipv6/route.c:1909
kobject: 'loop3' (000000002b424f37): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
  fib6_rule_lookup+0x12f/0x870 net/ipv6/fib6_rules.c:118
netlink: 188 bytes leftover after parsing attributes in process  
`syz-executor3'.
  ip6_route_input_lookup+0xb7/0xd0 net/ipv6/route.c:1921
  ip6_route_input+0x79b/0xe00 net/ipv6/route.c:2056
  ip6_rcv_finish_core.isra.0+0x204/0x720 net/ipv6/ip6_input.c:63
kobject: 'loop3' (000000002b424f37): kobject_uevent_env
  ip6_rcv_finish+0x109/0x330 net/ipv6/ip6_input.c:74
  NF_HOOK include/linux/netfilter.h:289 [inline]
  NF_HOOK include/linux/netfilter.h:283 [inline]
  ipv6_rcv+0x113/0x650 net/ipv6/ip6_input.c:272
kobject: 'loop3' (000000002b424f37): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
  __netif_receive_skb_one_core+0x160/0x210 net/core/dev.c:4973
  __netif_receive_skb+0x2c/0x1c0 net/core/dev.c:5083
  netif_receive_skb_internal+0x11e/0x690 net/core/dev.c:5186
  napi_frags_finish net/core/dev.c:5753 [inline]
  napi_gro_frags+0xd07/0xfe0 net/core/dev.c:5827
kobject: 'loop2' (00000000e55d2cdb): kobject_uevent_env
kobject: 'loop2' (00000000e55d2cdb): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
  tun_get_user+0x2ec2/0x4150 drivers/net/tun.c:1972
  tun_chr_write_iter+0xbd/0x160 drivers/net/tun.c:2017
  call_write_iter include/linux/fs.h:1857 [inline]
  do_iter_readv_writev+0x856/0xae0 fs/read_write.c:680
caif:caif_disconnect_client(): nothing to disconnect
  do_iter_write fs/read_write.c:959 [inline]
  do_iter_write+0x184/0x600 fs/read_write.c:940
  vfs_writev+0x1ee/0x370 fs/read_write.c:1004
  do_writev+0x11a/0x300 fs/read_write.c:1039
kobject: 'loop1' (00000000c17c68c7): kobject_uevent_env
  __do_sys_writev fs/read_write.c:1112 [inline]
  __se_sys_writev fs/read_write.c:1109 [inline]
  __x64_sys_writev+0x75/0xb0 fs/read_write.c:1109
kobject: 'loop1' (00000000c17c68c7): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
  do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457d81
Code: 75 14 b8 14 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a4 b8 fb ff c3 48  
83 ec 08 e8 1a 2d 00 00 48 89 04 24 b8 14 00 00 00 0f 05 <48> 8b 3c 24 48  
89 c2 e8 63 2d 00 00 48 89 d0 48 83 c4 08 48 3d 01
kobject: 'loop1' (00000000c17c68c7): kobject_uevent_env
RSP: 002b:00007fb67723dba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000000003e RCX: 0000000000457d81
RDX: 0000000000000001 RSI: 00007fb67723dbf0 RDI: 00000000000000f0
RBP: 00000000200001c0 R08: 00000000000000f0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00007fb67723e6d4
R13: 00000000004c636f R14: 00000000004db3f8 R15: 00000000ffffffff
Modules linked in:
---[ end trace b72be28f2a6c77c6 ]---
kobject: 'loop1' (00000000c17c68c7): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
RIP: 0010:rt6_make_pcpu_route net/ipv6/route.c:1260 [inline]
RIP: 0010:ip6_pol_route+0x82f/0x1490 net/ipv6/route.c:1893
Code: 48 03 1c c5 60 70 55 89 be 08 00 00 00 48 89 df e8 66 de f1 fa 31 c0  
f0 4c 0f b1 3b 48 85 c0 0f 84 b3 fb ff ff e8 d1 c0 ae fa <0f> 0b e8 ca c0  
ae fa e8 c5 8b 99 fa 31 ff 89 c6 88 85 c8 fe ff ff
RSP: 0018:ffff888092cb6dd0 EFLAGS: 00010212
RAX: 0000000000040000 RBX: ffffe8ffffc2e0b0 RCX: ffffc900061fb000
RDX: 0000000000000a5c RSI: ffffffff86d2e53f RDI: ffffe8ffffc2e0b0
RBP: ffff888092cb6f18 R08: 1ffffd1ffff85c16 R09: fffff91ffff85c17
R10: fffff91ffff85c16 R11: ffffe8ffffc2e0b7 R12: ffff88809b57e1c0
R13: 0000000000000001 R14: ffff888092cb6ef0 R15: ffff888088b0c640
FS:  00007fb67723e700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f817add4518 CR3: 0000000097a79000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

---
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