syzbot

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000083: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000418-0x000000000000041f]
CPU: 1 UID: 0 PID: 20445 Comm: syz.2.4360 Not tainted 6.17.0-rc1-syzkaller-00004-g53e760d89498 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:ip_ignore_linkdown include/linux/inetdevice.h:270 [inline]
RIP: 0010:fib_lookup_good_nhc+0xaf/0x3f0 net/ipv4/fib_trie.c:1408
Code: df 48 c1 ea 03 80 3c 02 00 0f 85 1e 03 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 2b 48 8d bd 18 04 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 ef 02 00 00 4c 8b bd 18 04 00 00 e8 4b 5d 7b 01
RSP: 0018:ffffc9000b74f6a0 EFLAGS: 00010212
RAX: dffffc0000000000 RBX: ffff888146f37220 RCX: ffffc90017f07000
RDX: 0000000000000083 RSI: ffffffff8a1613c9 RDI: 0000000000000418
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffc9000b74fa30
R13: ffff888146f37237 R14: 0000000000000001 R15: ffff88802f586b18
FS:  00007f4cc7ff66c0(0000) GS:ffff8881247c0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3738cb CR3: 0000000075f87000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 nexthop_get_nhc_lookup include/net/nexthop.h:437 [inline]
 fib_table_lookup+0x158e/0x2300 net/ipv4/fib_trie.c:1584
 fib_lookup.constprop.0+0x13e/0x530 include/net/ip_fib.h:390
 ip_route_output_key_hash_rcu+0xde8/0x28c0 net/ipv4/route.c:2805
 ip_route_output_key_hash+0x137/0x2e0 net/ipv4/route.c:2696
 __ip_route_output_key include/net/route.h:169 [inline]
 ip_route_output_flow+0x27/0x150 net/ipv4/route.c:2923
 ip_route_output_key include/net/route.h:179 [inline]
 sctp_v4_get_dst+0x3cf/0x1220 net/sctp/protocol.c:454
 sctp_transport_route+0x132/0x350 net/sctp/transport.c:457
 sctp_assoc_add_peer+0x741/0x1550 net/sctp/associola.c:663
 sctp_connect_new_asoc+0x1f8/0x770 net/sctp/socket.c:1100
 __sctp_connect+0x3f3/0xc60 net/sctp/socket.c:1198
 sctp_connect net/sctp/socket.c:4820 [inline]
 sctp_inet_connect+0x15f/0x200 net/sctp/socket.c:4835
 __sys_connect_file+0x141/0x1a0 net/socket.c:2086
 __sys_connect+0x13b/0x160 net/socket.c:2105
 __do_sys_connect net/socket.c:2111 [inline]
 __se_sys_connect net/socket.c:2108 [inline]
 __x64_sys_connect+0x72/0xb0 net/socket.c:2108
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4cc9d8ebe9
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:00007f4cc7ff6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f4cc9fb6180 RCX: 00007f4cc9d8ebe9
RDX: 0000000000000010 RSI: 0000200000004cc0 RDI: 0000000000000006
RBP: 00007f4cc9e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4cc9fb6218 R14: 00007f4cc9fb6180 R15: 00007ffc7227cef8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ip_ignore_linkdown include/linux/inetdevice.h:270 [inline]
RIP: 0010:fib_lookup_good_nhc+0xaf/0x3f0 net/ipv4/fib_trie.c:1408
Code: df 48 c1 ea 03 80 3c 02 00 0f 85 1e 03 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 2b 48 8d bd 18 04 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 ef 02 00 00 4c 8b bd 18 04 00 00 e8 4b 5d 7b 01
RSP: 0018:ffffc9000b74f6a0 EFLAGS: 00010212
RAX: dffffc0000000000 RBX: ffff888146f37220 RCX: ffffc90017f07000
RDX: 0000000000000083 RSI: ffffffff8a1613c9 RDI: 0000000000000418
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffc9000b74fa30
R13: ffff888146f37237 R14: 0000000000000001 R15: ffff88802f586b18
FS:  00007f4cc7ff66c0(0000) GS:ffff8881246c0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000015030 CR3: 0000000075f87000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	48 c1 ea 03          	shr    $0x3,%rdx
   4:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   8:	0f 85 1e 03 00 00    	jne    0x32c
   e:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  15:	fc ff df
  18:	48 8b 2b             	mov    (%rbx),%rbp
  1b:	48 8d bd 18 04 00 00 	lea    0x418(%rbp),%rdi
  22:	48 89 fa             	mov    %rdi,%rdx
  25:	48 c1 ea 03          	shr    $0x3,%rdx
* 29:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2d:	0f 85 ef 02 00 00    	jne    0x322
  33:	4c 8b bd 18 04 00 00 	mov    0x418(%rbp),%r15
  3a:	e8 4b 5d 7b 01       	call   0x17b5d8a