Re: INFO: trying to register non-static key in rhashtable_walk_enter

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit:    f49aa1de Merge tag 'for-5.2-rc1-tag' of git://git.kernel.o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1492b482a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fc045131472947d7
dashboard link: https://syzkaller.appspot.com/bug?extid=1e8114b61079bfe9cbc5
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
userspace arch: i386
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11baf8e4a00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13bf3d9ca00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1e8114b61079bfe9cbc5@xxxxxxxxxxxxxxxxxxxxxxxxx

INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
CPU: 1 PID: 8939 Comm: syz-executor164 Not tainted 5.2.0-rc1+ #1
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+0x172/0x1f0 lib/dump_stack.c:113
 assign_lock_key kernel/locking/lockdep.c:774 [inline]
 register_lock_class+0x167e/0x1860 kernel/locking/lockdep.c:1083
 __lock_acquire+0x116/0x5490 kernel/locking/lockdep.c:3673
 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4302
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151
 spin_lock include/linux/spinlock.h:338 [inline]
 rhashtable_walk_enter+0xf9/0x390 lib/rhashtable.c:669
 __tipc_dump_start+0x1fa/0x3c0 net/tipc/socket.c:3414
 tipc_dump_start+0x70/0x90 net/tipc/socket.c:3396
 __netlink_dump_start+0x4f8/0x7d0 net/netlink/af_netlink.c:2351
 netlink_dump_start include/linux/netlink.h:226 [inline]
 tipc_sock_diag_handler_dump+0x1d9/0x270 net/tipc/diag.c:91
 __sock_diag_cmd net/core/sock_diag.c:232 [inline]
 sock_diag_rcv_msg+0x319/0x410 net/core/sock_diag.c:263
 netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2486
 sock_diag_rcv+0x2b/0x40 net/core/sock_diag.c:274
 netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline]
 netlink_unicast+0x531/0x710 net/netlink/af_netlink.c:1337
 netlink_sendmsg+0x8ae/0xd70 net/netlink/af_netlink.c:1926
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:671
 ___sys_sendmsg+0x803/0x920 net/socket.c:2292
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2330
 __compat_sys_sendmsg net/compat.c:640 [inline]
 __do_compat_sys_sendmsg net/compat.c:647 [inline]
 __se_compat_sys_sendmsg net/compat.c:644 [inline]
 __ia32_compat_sys_sendmsg+0x7a/0xb0 net/compat.c:644
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x27b/0xd7d arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f2e849
Code: 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 14 24 c3 8b 3c 24 c3 90 90  
90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90  
90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000ffdfb03c EFLAGS: 00000246 ORIG_RAX: 0000000000000172
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020000040
RDX: 0000000000000000 RSI: 00000000080ea078 RDI: 00000000ffdfb090
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 8939 Comm: syz-executor164 Not tainted 5.2.0-rc1+ #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:list_add include/linux/list.h:79 [inline]
RIP: 0010:rhashtable_walk_enter+0x18f/0x390 lib/rhashtable.c:672
Code: c1 ea 03 80 3c 02 00 0f 85 ac 01 00 00 4d 8d 7e 10 4c 89 73 28 48 b8  
00 00 00 00 00 fc ff df 48 8d 4b 18 4c 89 fa 48 c1 ea 03 <80> 3c 02 00 0f  
85 70 01 00 00 49 8b 56 10 48 89 cf 4c 89 fe 48 89
RSP: 0018:ffff888089a17620 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff8880991f0f80 RCX: ffff8880991f0f98
RDX: 0000000000000002 RSI: ffffffff833391e4 RDI: ffff8880991f0fa8
RBP: ffff888089a17658 R08: ffff888096072480 R09: ffffed1011342eb2
R10: ffffed1011342eb1 R11: 0000000000000003 R12: ffff88809b30dc28
R13: ffff88809b30dd28 R14: 0000000000000000 R15: 0000000000000010
FS:  0000000000000000(0000) GS:ffff8880ae900000(0063) knlGS:0000000057838840
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000020000040 CR3: 000000009a614000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __tipc_dump_start+0x1fa/0x3c0 net/tipc/socket.c:3414
 tipc_dump_start+0x70/0x90 net/tipc/socket.c:3396
 __netlink_dump_start+0x4f8/0x7d0 net/netlink/af_netlink.c:2351
 netlink_dump_start include/linux/netlink.h:226 [inline]
 tipc_sock_diag_handler_dump+0x1d9/0x270 net/tipc/diag.c:91
 __sock_diag_cmd net/core/sock_diag.c:232 [inline]
 sock_diag_rcv_msg+0x319/0x410 net/core/sock_diag.c:263
 netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2486
 sock_diag_rcv+0x2b/0x40 net/core/sock_diag.c:274
 netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline]
 netlink_unicast+0x531/0x710 net/netlink/af_netlink.c:1337
 netlink_sendmsg+0x8ae/0xd70 net/netlink/af_netlink.c:1926
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:671
 ___sys_sendmsg+0x803/0x920 net/socket.c:2292
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2330
 __compat_sys_sendmsg net/compat.c:640 [inline]
 __do_compat_sys_sendmsg net/compat.c:647 [inline]
 __se_compat_sys_sendmsg net/compat.c:644 [inline]
 __ia32_compat_sys_sendmsg+0x7a/0xb0 net/compat.c:644
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x27b/0xd7d arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f2e849
Code: 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 14 24 c3 8b 3c 24 c3 90 90  
90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90  
90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000ffdfb03c EFLAGS: 00000246 ORIG_RAX: 0000000000000172
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020000040
RDX: 0000000000000000 RSI: 00000000080ea078 RDI: 00000000ffdfb090
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace df764217ca13e9ce ]---
RIP: 0010:list_add include/linux/list.h:79 [inline]
RIP: 0010:rhashtable_walk_enter+0x18f/0x390 lib/rhashtable.c:672
Code: c1 ea 03 80 3c 02 00 0f 85 ac 01 00 00 4d 8d 7e 10 4c 89 73 28 48 b8  
00 00 00 00 00 fc ff df 48 8d 4b 18 4c 89 fa 48 c1 ea 03 <80> 3c 02 00 0f  
85 70 01 00 00 49 8b 56 10 48 89 cf 4c 89 fe 48 89
RSP: 0018:ffff888089a17620 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff8880991f0f80 RCX: ffff8880991f0f98
RDX: 0000000000000002 RSI: ffffffff833391e4 RDI: ffff8880991f0fa8
RBP: ffff888089a17658 R08: ffff888096072480 R09: ffffed1011342eb2
R10: ffffed1011342eb1 R11: 0000000000000003 R12: ffff88809b30dc28
R13: ffff88809b30dd28 R14: 0000000000000000 R15: 0000000000000010
FS:  0000000000000000(0000) GS:ffff8880ae900000(0063) knlGS:0000000057838840
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000020000040 CR3: 000000009a614000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400