BUG: corrupted list in nft_obj_del

[syzbot <syzbot+6ca99af7e70e298bd09d@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    8b792f84 Merge branch 'mlxsw-Various-fixes'
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=1766b349e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7e89bd00623fe71e
dashboard link: https://syzkaller.appspot.com/bug?extid=6ca99af7e70e298bd09d
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=168b95e1e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10f29b3ee00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6ca99af7e70e298bd09d@syzkaller.appspotmail.com

list_del corruption, ffff8880a46b1500->prev is LIST_POISON2  
(dead000000000122)
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:48!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 9787 Comm: syz-executor290 Not tainted 5.5.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:__list_del_entry_valid.cold+0x37/0x4f lib/list_debug.c:48
Code: be fd 0f 0b 4c 89 ea 4c 89 f6 48 c7 c7 a0 65 71 88 e8 a0 bb be fd 0f  
0b 4c 89 e2 4c 89 f6 48 c7 c7 00 66 71 88 e8 8c bb be fd <0f> 0b 4c 89 f6  
48 c7 c7 c0 66 71 88 e8 7b bb be fd 0f 0b cc cc cc
RSP: 0018:ffffc900020e7338 EFLAGS: 00010286
RAX: 000000000000004e RBX: ffff8880a46b1500 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815e53a6 RDI: fffff5200041ce59
RBP: ffffc900020e7350 R08: 000000000000004e R09: ffffed1015d26621
R10: ffffed1015d26620 R11: ffff8880ae933107 R12: dead000000000122
R13: ffff88809e9c3970 R14: ffff8880a46b1500 R15: ffff8880a46b1508
FS:  0000000000837880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000280 CR3: 000000008f0b6000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  __list_del_entry include/linux/list.h:131 [inline]
  list_del_rcu include/linux/rculist.h:148 [inline]
  nft_obj_del+0xcb/0x1f0 net/netfilter/nf_tables_api.c:6970
  nf_tables_commit+0x1339/0x3b30 net/netfilter/nf_tables_api.c:7171
  nfnetlink_rcv_batch+0xc78/0x17a0 net/netfilter/nfnetlink.c:485
  nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:543 [inline]
  nfnetlink_rcv+0x3e7/0x460 net/netfilter/nfnetlink.c:561
  netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
  netlink_unicast+0x58c/0x7d0 net/netlink/af_netlink.c:1328
  netlink_sendmsg+0x91c/0xea0 net/netlink/af_netlink.c:1917
  sock_sendmsg_nosec net/socket.c:639 [inline]
  sock_sendmsg+0xd7/0x130 net/socket.c:659
  ____sys_sendmsg+0x753/0x880 net/socket.c:2330
  ___sys_sendmsg+0x100/0x170 net/socket.c:2384
  __sys_sendmsg+0x105/0x1d0 net/socket.c:2417
  __do_sys_sendmsg net/socket.c:2426 [inline]
  __se_sys_sendmsg net/socket.c:2424 [inline]
  __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2424
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4406a9
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:00007fff37625bc8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004406a9
RDX: 0000000000042000 RSI: 0000000020000140 RDI: 0000000000000004
RBP: 00000000006ca018 R08: 0000000000000001 R09: 00000000004002c8
R10: 0000000000000009 R11: 0000000000000246 R12: 0000000000401f30
R13: 0000000000401fc0 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 7b3c7a3aadb229c5 ]---
RIP: 0010:__list_del_entry_valid.cold+0x37/0x4f lib/list_debug.c:48
Code: be fd 0f 0b 4c 89 ea 4c 89 f6 48 c7 c7 a0 65 71 88 e8 a0 bb be fd 0f  
0b 4c 89 e2 4c 89 f6 48 c7 c7 00 66 71 88 e8 8c bb be fd <0f> 0b 4c 89 f6  
48 c7 c7 c0 66 71 88 e8 7b bb be fd 0f 0b cc cc cc
RSP: 0018:ffffc900020e7338 EFLAGS: 00010286
RAX: 000000000000004e RBX: ffff8880a46b1500 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815e53a6 RDI: fffff5200041ce59
RBP: ffffc900020e7350 R08: 000000000000004e R09: ffffed1015d26621
R10: ffffed1015d26620 R11: ffff8880ae933107 R12: dead000000000122
R13: ffff88809e9c3970 R14: ffff8880a46b1500 R15: ffff8880a46b1508
FS:  0000000000837880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000280 CR3: 000000008f0b6000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
This bug 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 bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches