general protection fault, probably for non-canonical address 0xdffffc000000005b: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x00000000000002d8-0x00000000000002df] CPU: 1 PID: 11157 Comm: syz.8.2843 Not tainted 5.10.240-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:ip_ignore_linkdown include/linux/inetdevice.h:254 [inline] RIP: 0010:fib_lookup_good_nhc net/ipv4/fib_trie.c:1363 [inline] RIP: 0010:nexthop_get_nhc_lookup+0x1a2/0x6c0 include/net/nexthop.h:291 Code: 74 08 48 89 df e8 5e aa bf fd 48 89 5d a8 48 8b 1b b8 d8 02 00 00 48 01 c3 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 30 aa bf fd 48 8b 1b 48 85 db 74 68 RSP: 0018:ffffc90000faf200 EFLAGS: 00010202 RAX: 000000000000005b RBX: 00000000000002d8 RCX: dffffc0000000000 RDX: ffff88810d282780 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000faf270 R08: dffffc0000000000 R09: ffffc90000faf5b8 R10: fffff520001f5eb9 R11: 1ffff920001f5eb7 R12: ffff8881274bc000 R13: 0000000000000000 R14: 0000000000000000 R15: ffff888110708b10 FS: 00007f1b1fe506c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c2f6af4 CR3: 00000001222c7000 CR4: 00000000003506a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: fib_table_lookup+0xe4c/0x1730 net/ipv4/fib_trie.c:1542 fib_lookup include/net/ip_fib.h:379 [inline] ip_route_input_slow net/ipv4/route.c:2223 [inline] ip_route_input_rcu+0x1335/0x2530 net/ipv4/route.c:2415 ip_route_input_noref+0xbb/0x110 net/ipv4/route.c:2360 ip_rcv_finish_core+0x3ef/0x12d0 net/ipv4/ip_input.c:361 ip_rcv_finish net/ipv4/ip_input.c:434 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] ip_rcv+0xe0/0x270 net/ipv4/ip_input.c:547 __netif_receive_skb_one_core net/core/dev.c:5402 [inline] __netif_receive_skb+0xc8/0x280 net/core/dev.c:5516 netif_receive_skb_internal net/core/dev.c:5621 [inline] netif_receive_skb+0x9b/0x3d0 net/core/dev.c:5680 tun_rx_batched+0x5e8/0x710 drivers/net/tun.c:-1 tun_get_user+0x25d0/0x3090 drivers/net/tun.c:2026 tun_chr_write_iter+0x1bf/0x270 drivers/net/tun.c:2059 call_write_iter include/linux/fs.h:2066 [inline] new_sync_write fs/read_write.c:518 [inline] vfs_write+0x725/0xd60 fs/read_write.c:605 ksys_write+0x140/0x240 fs/read_write.c:658 __do_sys_write fs/read_write.c:670 [inline] __se_sys_write fs/read_write.c:667 [inline] __x64_sys_write+0x7b/0x90 fs/read_write.c:667 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7f1b213e669f Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48 RSP: 002b:00007f1b1fe50000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f1b2160efa0 RCX: 00007f1b213e669f RDX: 0000000000000036 RSI: 0000200000000380 RDI: 00000000000000c8 RBP: 00007f1b2146ae19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000036 R11: 0000000000000293 R12: 0000000000000000 R13: 00007f1b2160f038 R14: 00007f1b2160efa0 R15: 00007ffe6ce61b88 Modules linked in: ---[ end trace b18772f1db340ba5 ]--- RIP: 0010:ip_ignore_linkdown include/linux/inetdevice.h:254 [inline] RIP: 0010:fib_lookup_good_nhc net/ipv4/fib_trie.c:1363 [inline] RIP: 0010:nexthop_get_nhc_lookup+0x1a2/0x6c0 include/net/nexthop.h:291 Code: 74 08 48 89 df e8 5e aa bf fd 48 89 5d a8 48 8b 1b b8 d8 02 00 00 48 01 c3 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 30 aa bf fd 48 8b 1b 48 85 db 74 68 RSP: 0018:ffffc90000faf200 EFLAGS: 00010202 RAX: 000000000000005b RBX: 00000000000002d8 RCX: dffffc0000000000 RDX: ffff88810d282780 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000faf270 R08: dffffc0000000000 R09: ffffc90000faf5b8 R10: fffff520001f5eb9 R11: 1ffff920001f5eb7 R12: ffff8881274bc000 R13: 0000000000000000 R14: 0000000000000000 R15: ffff888110708b10 FS: 00007f1b1fe506c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c2f6af4 CR3: 00000001222c7000 CR4: 00000000003506a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 74 08 je 0xa 2: 48 89 df mov %rbx,%rdi 5: e8 5e aa bf fd call 0xfdbfaa68 a: 48 89 5d a8 mov %rbx,-0x58(%rbp) e: 48 8b 1b mov (%rbx),%rbx 11: b8 d8 02 00 00 mov $0x2d8,%eax 16: 48 01 c3 add %rax,%rbx 19: 48 89 d8 mov %rbx,%rax 1c: 48 c1 e8 03 shr $0x3,%rax 20: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx 27: fc ff df * 2a: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction 2e: 74 08 je 0x38 30: 48 89 df mov %rbx,%rdi 33: e8 30 aa bf fd call 0xfdbfaa68 38: 48 8b 1b mov (%rbx),%rbx 3b: 48 85 db test %rbx,%rbx 3e: 74 68 je 0xa8