BUG: corrupted list in rhashtable_walk_enter

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    a5ed1e96 Merge tag 'powerpc-5.1-3' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1788d34d200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9a31fb246de2a622
dashboard link: https://syzkaller.appspot.com/bug?extid=dae72a112334aa65a159
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11d40c07200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+dae72a112334aa65a159@xxxxxxxxxxxxxxxxxxxxxxxxx

list_add corruption. next->prev should be prev (ffff888091d3aa60), but was  
0000000000000002. (next=ffff8880984df5f0).
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:23!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 11985 Comm: syz-executor.4 Not tainted 5.1.0-rc1+ #34
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:__list_add_valid.cold+0xf/0x3c lib/list_debug.c:23
Code: 77 fe eb d5 4c 89 e7 e8 ba 6a 77 fe eb a3 4c 89 f7 e8 b0 6a 77 fe e9  
56 ff ff ff 4c 89 e1 48 c7 c7 00 d5 a1 87 e8 f0 ce 29 fe <0f> 0b 48 89 f2  
4c 89 e1 4c 89 ee 48 c7 c7 40 d6 a1 87 e8 d9 ce 29
RSP: 0018:ffff888085b3f4b0 EFLAGS: 00010286
RAX: 0000000000000075 RBX: ffff888085b3f5d8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815ae266 RDI: ffffed1010b67e88
RBP: ffff888085b3f4c8 R08: 0000000000000075 R09: ffffed1015d05011
R10: ffffed1015d05010 R11: ffff8880ae828087 R12: ffff8880984df5f0
R13: ffff888085b3f5f0 R14: ffff888091d3aa40 R15: ffff888091d3aa60
FS:  00007f7a35de9700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000000 CR3: 00000000a61fa000 CR4: 00000000001406f0
Call Trace:
 __list_add include/linux/list.h:60 [inline]
 list_add include/linux/list.h:79 [inline]
 rhashtable_walk_enter+0x1b0/0x390 lib/rhashtable.c:676
 ila_xlat_nl_cmd_flush+0x244/0x1090 net/ipv6/ila/ila_xlat.c:388
 genl_family_rcv_msg+0x6e1/0xd90 net/netlink/genetlink.c:601
 genl_rcv_msg+0xca/0x16c net/netlink/genetlink.c:626
 netlink_rcv_skb+0x17a/0x460 net/netlink/af_netlink.c:2485
 genl_rcv+0x29/0x40 net/netlink/genetlink.c:637
 netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
 netlink_unicast+0x536/0x720 net/netlink/af_netlink.c:1336
 netlink_sendmsg+0x8ae/0xd70 net/netlink/af_netlink.c:1925
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xdd/0x130 net/socket.c:632
 ___sys_sendmsg+0x806/0x930 net/socket.c:2137
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2175
 __do_sys_sendmsg net/socket.c:2184 [inline]
 __se_sys_sendmsg net/socket.c:2182 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2182
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458209
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7a35de8c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458209
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7a35de96d4
R13: 00000000004c57c8 R14: 00000000004d96b8 R15: 00000000ffffffff
Modules linked in:
---[ end trace 25c5a70a6fa97765 ]---
RIP: 0010:__list_add_valid.cold+0xf/0x3c lib/list_debug.c:23
Code: 77 fe eb d5 4c 89 e7 e8 ba 6a 77 fe eb a3 4c 89 f7 e8 b0 6a 77 fe e9  
56 ff ff ff 4c 89 e1 48 c7 c7 00 d5 a1 87 e8 f0 ce 29 fe <0f> 0b 48 89 f2  
4c 89 e1 4c 89 ee 48 c7 c7 40 d6 a1 87 e8 d9 ce 29
RSP: 0018:ffff888085b3f4b0 EFLAGS: 00010286
RAX: 0000000000000075 RBX: ffff888085b3f5d8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815ae266 RDI: ffffed1010b67e88
RBP: ffff888085b3f4c8 R08: 0000000000000075 R09: ffffed1015d05011
R10: ffffed1015d05010 R11: ffff8880ae828087 R12: ffff8880984df5f0
R13: ffff888085b3f5f0 R14: ffff888091d3aa40 R15: ffff888091d3aa60
FS:  00007f7a35de9700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000000 CR3: 00000000a61fa000 CR4: 00000000001406f0


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