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: 5978 Comm: syz.5.501 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 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 8f 58 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 70 58 51 f9 4d 8b 24 24 e8 47 19 RSP: 0018:ffffc900035af098 EFLAGS: 00010202 RAX: 000000000000006b RBX: ffff888074e66c20 RCX: ffff888077588000 RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff888074e66c2f R08: dffffc0000000000 R09: fffffbfff1ff7819 R10: fffffbfff1ff7819 R11: 1ffffffff1ff7818 R12: 0000000000000358 R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff1100e9ccd85 FS: 00007f17942f76c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c3940c1 CR3: 0000000059791000 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 fib_lookup+0x192/0x400 include/net/ip_fib.h:381 ip_route_output_key_hash_rcu+0x2ec/0x24d0 net/ipv4/route.c:2788 ip_route_output_key_hash+0x1b1/0x2e0 net/ipv4/route.c:2678 __ip_route_output_key include/net/route.h:126 [inline] ip_route_output_flow+0x26/0x150 net/ipv4/route.c:2908 udp_sendmsg+0x159f/0x2340 net/ipv4/udp.c:1245 udpv6_sendmsg+0x92f/0x2320 net/ipv6/udp.c:1395 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_sendmsg net/socket.c:2519 [inline] __do_sys_sendmsg net/socket.c:2528 [inline] __se_sys_sendmsg+0x190/0x250 net/socket.c:2526 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: 0033:0x7f179608fec9 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:00007f17942f7038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f17962e6fa0 RCX: 00007f179608fec9 RDX: 0000000000000000 RSI: 0000200000000400 RDI: 0000000000000007 RBP: 00007f1796112f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f17962e7038 R14: 00007f17962e6fa0 R15: 00007ffd9bcd2698 Modules linked in: ---[ end trace 0d5d176943083c9b ]--- 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 8f 58 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 70 58 51 f9 4d 8b 24 24 e8 47 19 RSP: 0018:ffffc900035af098 EFLAGS: 00010202 RAX: 000000000000006b RBX: ffff888074e66c20 RCX: ffff888077588000 RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff888074e66c2f R08: dffffc0000000000 R09: fffffbfff1ff7819 R10: fffffbfff1ff7819 R11: 1ffffffff1ff7818 R12: 0000000000000358 R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff1100e9ccd85 FS: 00007f17942f76c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f103d24af98 CR3: 0000000059791000 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 8f 58 51 f9 call 0xf95158a9 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 70 58 51 f9 call 0xf95158a9 39: 4d 8b 24 24 mov (%r12),%r12 3d: e8 .byte 0xe8 3e: 47 rex.RXB 3f: 19 .byte 0x19