Oops: general protection fault, probably for non-canonical address 0xdffffc0000000083: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000418-0x000000000000041f] CPU: 1 UID: 0 PID: 32546 Comm: syz.0.7701 Not tainted syzkaller #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+0x85/0x3d0 net/ipv4/fib_trie.c:1408 Code: 4c 89 24 24 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 bb 08 1b f8 41 bc 18 04 00 00 4c 03 23 4c 89 e0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 e7 e8 9c 08 1b f8 4d 8b 24 24 e8 e3 c7 RSP: 0018:ffffc9000eb6ebb0 EFLAGS: 00010202 RAX: 0000000000000083 RBX: ffff88806363c320 RCX: 0000000000000002 RDX: ffff88802b329e00 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88806363c337 R08: 0000000000000000 R09: ffffffff8a0e0b4f R10: 0000000000000008 R11: 0000000000000002 R12: 0000000000000418 R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff1100c6c7866 FS: 0000000000000000(0000) GS:ffff888125d18000(0063) knlGS:00000000f5456b40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 000000000c42e383 CR3: 0000000029176000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 000000000000000e DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: nexthop_get_nhc_lookup+0x1af/0x400 include/net/nexthop.h:437 fib_table_lookup+0xf26/0x16e0 net/ipv4/fib_trie.c:1584 fib4_rule_action+0x1fb/0x330 net/ipv4/fib_rules.c:138 fib_rules_lookup+0x8a6/0xe90 net/core/fib_rules.c:339 __fib_lookup+0xf9/0x200 net/ipv4/fib_rules.c:95 __fib_validate_source net/ipv4/fib_frontend.c:379 [inline] fib_validate_source+0x54f/0x1010 net/ipv4/fib_frontend.c:458 fib_validate_source_reason include/net/ip_fib.h:462 [inline] ip_route_input_slow net/ipv4/route.c:2368 [inline] ip_route_input_rcu+0x242c/0x2ff0 net/ipv4/route.c:2537 ip_route_input_noref+0x167/0x250 net/ipv4/route.c:2548 ip_rcv_finish_core+0x5af/0x1c00 net/ipv4/ip_input.c:371 ip_rcv_finish+0x14c/0x2f0 net/ipv4/ip_input.c:452 NF_HOOK+0x309/0x3a0 include/linux/netfilter.h:318 __netif_receive_skb_one_core net/core/dev.c:5991 [inline] __netif_receive_skb+0x143/0x380 net/core/dev.c:6104 netif_receive_skb_internal net/core/dev.c:6190 [inline] netif_receive_skb+0x1cb/0x790 net/core/dev.c:6249 tun_rx_batched+0x1b9/0x730 drivers/net/tun.c:1485 tun_get_user+0x2aa2/0x3e20 drivers/net/tun.c:1950 tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xb6/0x2b0 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x34/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf7f46539 Code: 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 002b:00000000f545655c EFLAGS: 00000206 ORIG_RAX: 0000000000000004 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000080000280 RDX: 000000000000004e RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:ip_ignore_linkdown include/linux/inetdevice.h:270 [inline] RIP: 0010:fib_lookup_good_nhc+0x85/0x3d0 net/ipv4/fib_trie.c:1408 Code: 4c 89 24 24 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 bb 08 1b f8 41 bc 18 04 00 00 4c 03 23 4c 89 e0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 e7 e8 9c 08 1b f8 4d 8b 24 24 e8 e3 c7 RSP: 0018:ffffc9000eb6ebb0 EFLAGS: 00010202 RAX: 0000000000000083 RBX: ffff88806363c320 RCX: 0000000000000002 RDX: ffff88802b329e00 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88806363c337 R08: 0000000000000000 R09: ffffffff8a0e0b4f R10: 0000000000000008 R11: 0000000000000002 R12: 0000000000000418 R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff1100c6c7866 FS: 0000000000000000(0000) GS:ffff888125d18000(0063) knlGS:00000000f5456b40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 000000000c42e383 CR3: 0000000029176000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 000000000000000e DR6: 00000000ffff0ff0 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 bb 08 1b f8 call 0xf81b08d5 1a: 41 bc 18 04 00 00 mov $0x418,%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 9c 08 1b f8 call 0xf81b08d5 39: 4d 8b 24 24 mov (%r12),%r12 3d: e8 .byte 0xe8 3e: e3 c7 jrcxz 0x7