netlink: 8 bytes leftover after parsing attributes in process `syz.6.1768'. general protection fault, probably for non-canonical address 0xdffffc000000006b: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000358-0x000000000000035f] CPU: 1 PID: 11256 Comm: syz.6.1768 Not tainted 5.15.189-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:ip_ignore_linkdown include/linux/inetdevice.h:254 [inline] RIP: 0010:fib_lookup_good_nhc+0x81/0x3d0 net/ipv4/fib_trie.c:1407 Code: 4c 89 24 24 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 ff f3 51 f9 41 bc 58 03 00 00 4c 03 23 4c 89 e0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 e7 e8 e0 f3 51 f9 4d 8b 24 24 e8 a7 ff RSP: 0018:ffffc9000363f0b8 EFLAGS: 00010202 RAX: 000000000000006b RBX: ffff8880610d6d20 RCX: ffff888070aa1dc0 RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff8880610d6d2f R08: dffffc0000000000 R09: fffffbfff1ff6e19 R10: fffffbfff1ff6e19 R11: 1ffffffff1ff6e18 R12: 0000000000000358 R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff1100c21ada5 FS: 00007f99507ce6c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b32015ff8 CR3: 0000000057ad6000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: nexthop_get_nhc_lookup+0x1a8/0x400 include/net/nexthop.h:405 fib_table_lookup+0xe76/0x15e0 net/ipv4/fib_trie.c:1583 fib4_rule_action+0x1cf/0x2f0 net/ipv4/fib_rules.c:135 fib_rules_lookup+0x5ab/0xaf0 net/core/fib_rules.c:318 __fib_lookup+0xf6/0x200 net/ipv4/fib_rules.c:92 ip_route_output_key_hash_rcu+0x305/0x2460 net/ipv4/route.c:2785 ip_route_output_key_hash+0x1b1/0x2e0 net/ipv4/route.c:2675 __ip_route_output_key include/net/route.h:126 [inline] ip_route_output_flow+0x26/0x150 net/ipv4/route.c:2905 udp_sendmsg+0x159f/0x2340 net/ipv4/udp.c:1245 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] ____sys_sendmsg+0x5a2/0x8c0 net/socket.c:2436 ___sys_sendmsg+0x1f0/0x260 net/socket.c:2490 __sys_sendmmsg+0x27c/0x4a0 net/socket.c:2576 __do_sys_sendmmsg net/socket.c:2605 [inline] __se_sys_sendmmsg net/socket.c:2602 [inline] __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2602 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f9952566be9 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:00007f99507ce038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f995278dfa0 RCX: 00007f9952566be9 RDX: 0000000000000001 RSI: 0000200000000e00 RDI: 0000000000000006 RBP: 00007f99525e9e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f995278e038 R14: 00007f995278dfa0 R15: 00007fffecdbbab8 Modules linked in: ---[ end trace 6620603b936654eb ]--- RIP: 0010:ip_ignore_linkdown include/linux/inetdevice.h:254 [inline] RIP: 0010:fib_lookup_good_nhc+0x81/0x3d0 net/ipv4/fib_trie.c:1407 Code: 4c 89 24 24 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 ff f3 51 f9 41 bc 58 03 00 00 4c 03 23 4c 89 e0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 e7 e8 e0 f3 51 f9 4d 8b 24 24 e8 a7 ff RSP: 0018:ffffc9000363f0b8 EFLAGS: 00010202 RAX: 000000000000006b RBX: ffff8880610d6d20 RCX: ffff888070aa1dc0 RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff8880610d6d2f R08: dffffc0000000000 R09: fffffbfff1ff6e19 R10: fffffbfff1ff6e19 R11: 1ffffffff1ff6e18 R12: 0000000000000358 R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff1100c21ada5 FS: 00007f99507ce6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ff189b06000 CR3: 0000000057ad6000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 4c 89 24 24 mov %r12,(%rsp) 4: 48 89 d8 mov %rbx,%rax 7: 48 c1 e8 03 shr $0x3,%rax b: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) 10: 74 08 je 0x1a 12: 48 89 df mov %rbx,%rdi 15: e8 ff f3 51 f9 call 0xf951f419 1a: 41 bc 58 03 00 00 mov $0x358,%r12d 20: 4c 03 23 add (%rbx),%r12 23: 4c 89 e0 mov %r12,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction 2f: 74 08 je 0x39 31: 4c 89 e7 mov %r12,%rdi 34: e8 e0 f3 51 f9 call 0xf951f419 39: 4d 8b 24 24 mov (%r12),%r12 3d: e8 .byte 0xe8 3e: a7 cmpsl %es:(%rdi),%ds:(%rsi) 3f: ff .byte 0xff