syzbot

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000012: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097]
CPU: 0 UID: 0 PID: 36 Comm: kworker/u8:2 Not tainted 6.16.0-rc5-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: netns cleanup_net
RIP: 0010:__fib6_drop_pcpu_from+0x1f0/0x3b0 net/ipv6/ip6_fib.c:992
Code: 48 c1 e8 03 42 80 3c 30 00 74 08 4c 89 ef e8 47 0a 00 f8 49 8b 6d 00 48 85 ed 74 2f 48 81 c5 90 00 00 00 48 89 e8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 ef e8 21 0a 00 f8 48 8b 45 00 48 3b 44
RSP: 0018:ffffc90000ac6ba8 EFLAGS: 00010206
RAX: 0000000000000012 RBX: ffffffff8dba8c60 RCX: ffff888142ec1e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000091 R08: 0000000000000000 R09: ffffffff8a217106
R10: dffffc0000000000 R11: fffffbfff1f4177f R12: 0000000000000000
R13: ffffe8ffffc4d780 R14: dffffc0000000000 R15: ffff888034940120
FS:  0000000000000000(0000) GS:ffff888125c51000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f272514c000 CR3: 00000000331de000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 fib6_drop_pcpu_from net/ipv6/ip6_fib.c:1037 [inline]
 fib6_purge_rt+0x172/0x9b0 net/ipv6/ip6_fib.c:1048
 fib6_del_route net/ipv6/ip6_fib.c:2048 [inline]
 fib6_del+0xee1/0x1550 net/ipv6/ip6_fib.c:2093
 fib6_clean_node+0x29f/0x590 net/ipv6/ip6_fib.c:2255
 fib6_walk_continue+0x678/0x910 net/ipv6/ip6_fib.c:2177
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2225
 fib6_clean_tree net/ipv6/ip6_fib.c:2305 [inline]
 __fib6_clean_all+0x234/0x380 net/ipv6/ip6_fib.c:2321
 rt6_sync_down_dev net/ipv6/route.c:5004 [inline]
 rt6_disable_ip+0x120/0x720 net/ipv6/route.c:5009
 addrconf_ifdown+0x15d/0x1880 net/ipv6/addrconf.c:3857
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b6/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 dev_close_many+0x29c/0x410 net/core/dev.c:1785
 unregister_netdevice_many_notify+0x834/0x2320 net/core/dev.c:12047
 unregister_netdevice_many net/core/dev.c:12140 [inline]
 default_device_exit_batch+0x819/0x890 net/core/dev.c:12644
 ops_exit_list net/core/net_namespace.c:206 [inline]
 ops_undo_list+0x525/0x990 net/core/net_namespace.c:253
 cleanup_net+0x4c5/0x800 net/core/net_namespace.c:686
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x711/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__fib6_drop_pcpu_from+0x1f0/0x3b0 net/ipv6/ip6_fib.c:992
Code: 48 c1 e8 03 42 80 3c 30 00 74 08 4c 89 ef e8 47 0a 00 f8 49 8b 6d 00 48 85 ed 74 2f 48 81 c5 90 00 00 00 48 89 e8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 ef e8 21 0a 00 f8 48 8b 45 00 48 3b 44
RSP: 0018:ffffc90000ac6ba8 EFLAGS: 00010206
RAX: 0000000000000012 RBX: ffffffff8dba8c60 RCX: ffff888142ec1e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000091 R08: 0000000000000000 R09: ffffffff8a217106
R10: dffffc0000000000 R11: fffffbfff1f4177f R12: 0000000000000000
R13: ffffe8ffffc4d780 R14: dffffc0000000000 R15: ffff888034940120
FS:  0000000000000000(0000) GS:ffff888125c51000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f272514c000 CR3: 00000000331de000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	48 c1 e8 03          	shr    $0x3,%rax
   4:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1)
   9:	74 08                	je     0x13
   b:	4c 89 ef             	mov    %r13,%rdi
   e:	e8 47 0a 00 f8       	call   0xf8000a5a
  13:	49 8b 6d 00          	mov    0x0(%r13),%rbp
  17:	48 85 ed             	test   %rbp,%rbp
  1a:	74 2f                	je     0x4b
  1c:	48 81 c5 90 00 00 00 	add    $0x90,%rbp
  23:	48 89 e8             	mov    %rbp,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	48 89 ef             	mov    %rbp,%rdi
  34:	e8 21 0a 00 f8       	call   0xf8000a5a
  39:	48 8b 45 00          	mov    0x0(%rbp),%rax
  3d:	48                   	rex.W
  3e:	3b                   	.byte 0x3b
  3f:	44                   	rex.R