syzbot

netlink: 28 bytes leftover after parsing attributes in process `syz.0.382'.
geneve1: entered allmulticast mode
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 UID: 0 PID: 7569 Comm: syz.0.382 Not tainted 6.13.0-rc5-syzkaller-00006-g56e6a3499e14 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:sctp_inet6addr_event+0x175/0x900 net/sctp/ipv6.c:100
Code: 00 00 00 00 fc ff df 48 89 04 24 48 c1 e8 03 4c 01 e8 48 89 44 24 18 eb 31 e8 97 15 31 f7 4c 89 e0 48 c1 e8 03 4c 89 64 24 38 <42> 80 3c 28 00 0f 85 88 05 00 00 4c 39 64 24 40 4c 89 e3 49 8b 04
RSP: 0018:ffffc90005076be0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8881413fff00 RCX: ffffc9000ec69000
RDX: 0000000000080000 RSI: ffffffff8a683a29 RDI: 0000000000000003
RBP: ffffc90005076c50 R08: 0000000000000003 R09: 000000000000000a
R10: 0000000000000000 R11: 0000000000000002 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff888033a28c00 R15: 0000000000000000
FS:  00007f9cbe56c6c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2fd20224 CR3: 000000001cb2c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 notifier_call_chain+0xb7/0x410 kernel/notifier.c:85
 atomic_notifier_call_chain+0x71/0x1c0 kernel/notifier.c:223
 addrconf_ifdown.isra.0+0xf06/0x1a20 net/ipv6/addrconf.c:4002
 addrconf_notify+0x220/0x19c0 net/ipv6/addrconf.c:3800
 notifier_call_chain+0xb7/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:1996
 call_netdevice_notifiers_extack net/core/dev.c:2034 [inline]
 call_netdevice_notifiers net/core/dev.c:2048 [inline]
 __dev_notify_flags+0x1f9/0x2e0 net/core/dev.c:8990
 dev_change_flags+0x10c/0x160 net/core/dev.c:9026
 do_setlink.constprop.0+0x17b9/0x3f20 net/core/rtnetlink.c:3109
 rtnl_changelink net/core/rtnetlink.c:3723 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3875 [inline]
 rtnl_newlink+0x131c/0x1d70 net/core/rtnetlink.c:4012
 rtnetlink_rcv_msg+0x95b/0xea0 net/core/rtnetlink.c:6922
 netlink_rcv_skb+0x165/0x410 net/netlink/af_netlink.c:2542
 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]
 netlink_unicast+0x53c/0x7f0 net/netlink/af_netlink.c:1347
 netlink_sendmsg+0x8b8/0xd70 net/netlink/af_netlink.c:1891
 sock_sendmsg_nosec net/socket.c:711 [inline]
 __sock_sendmsg net/socket.c:726 [inline]
 ____sys_sendmsg+0x9ae/0xb40 net/socket.c:2583
 ___sys_sendmsg+0x135/0x1e0 net/socket.c:2637
 __sys_sendmmsg+0x201/0x420 net/socket.c:2726
 __do_sys_sendmmsg net/socket.c:2753 [inline]
 __se_sys_sendmmsg net/socket.c:2750 [inline]
 __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2750
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9cbd785d29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9cbe56c038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f9cbd976160 RCX: 00007f9cbd785d29
RDX: 0000000000000007 RSI: 0000000020000200 RDI: 0000000000000004
RBP: 00007f9cbd801b08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004008 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f9cbd976160 R15: 00007fff7d42e458
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:sctp_inet6addr_event+0x175/0x900 net/sctp/ipv6.c:100
Code: 00 00 00 00 fc ff df 48 89 04 24 48 c1 e8 03 4c 01 e8 48 89 44 24 18 eb 31 e8 97 15 31 f7 4c 89 e0 48 c1 e8 03 4c 89 64 24 38 <42> 80 3c 28 00 0f 85 88 05 00 00 4c 39 64 24 40 4c 89 e3 49 8b 04
RSP: 0018:ffffc90005076be0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8881413fff00 RCX: ffffc9000ec69000
RDX: 0000000000080000 RSI: ffffffff8a683a29 RDI: 0000000000000003
RBP: ffffc90005076c50 R08: 0000000000000003 R09: 000000000000000a
R10: 0000000000000000 R11: 0000000000000002 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff888033a28c00 R15: 0000000000000000
FS:  00007f9cbe56c6c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2fd20224 CR3: 000000001cb2c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 6 bytes skipped:
   0:	df 48 89             	fisttps -0x77(%rax)
   3:	04 24                	add    $0x24,%al
   5:	48 c1 e8 03          	shr    $0x3,%rax
   9:	4c 01 e8             	add    %r13,%rax
   c:	48 89 44 24 18       	mov    %rax,0x18(%rsp)
  11:	eb 31                	jmp    0x44
  13:	e8 97 15 31 f7       	call   0xf73115af
  18:	4c 89 e0             	mov    %r12,%rax
  1b:	48 c1 e8 03          	shr    $0x3,%rax
  1f:	4c 89 64 24 38       	mov    %r12,0x38(%rsp)
* 24:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1) <-- trapping instruction
  29:	0f 85 88 05 00 00    	jne    0x5b7
  2f:	4c 39 64 24 40       	cmp    %r12,0x40(%rsp)
  34:	4c 89 e3             	mov    %r12,%rbx
  37:	49                   	rex.WB
  38:	8b                   	.byte 0x8b
  39:	04                   	.byte 0x4