syzbot


general protection fault in nexthop_get_nhc_lookup

Status: premoderation: reported on 2025/07/09 23:30
Reported-by: syzbot+08dfae76b29663915743@syzkaller.appspotmail.com
First crash: 17d, last: 2d12h

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc000000005b: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000002d8-0x00000000000002df]
CPU: 0 PID: 17412 Comm: kworker/u4:7 Tainted: G        W         5.10.240-syzkaller-00213-gad9a98ef27a4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker
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 be 08 c1 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 90 08 c1 fd 48 8b 1b 48 85 db 74 68
RSP: 0018:ffffc900010ef468 EFLAGS: 00010202
RAX: 000000000000005b RBX: 00000000000002d8 RCX: dffffc0000000000
RDX: ffff8881444493c0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900010ef4d8 R08: ffff8881444493c0 R09: 0000000000000003
R10: 0000000000000008 R11: 0000000000000000 R12: ffff888117410b00
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88811886cc90
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffd88f0000 CR3: 0000000121c97000 CR4: 00000000003506b0
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
 fib4_rule_action+0x115/0x1a0 net/ipv4/fib_rules.c:135
 fib_rules_lookup+0x489/0x8d0 net/core/fib_rules.c:318
 __fib_lookup+0xe4/0x150 net/ipv4/fib_rules.c:92
 fib_lookup include/net/ip_fib.h:371 [inline]
 ip_route_output_key_hash_rcu+0x329/0x2060 net/ipv4/route.c:2671
 ip_route_output_key_hash net/ipv4/route.c:2561 [inline]
 __ip_route_output_key include/net/route.h:126 [inline]
 ip_route_output_flow+0x123/0x2d0 net/ipv4/route.c:2793
 send4+0x312/0x990 drivers/net/wireguard/socket.c:61
 wg_socket_send_skb_to_peer+0xd4/0x1d0 drivers/net/wireguard/socket.c:175
 wg_socket_send_buffer_to_peer+0x118/0x170 drivers/net/wireguard/socket.c:200
 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
 wg_packet_handshake_send_worker+0x1d4/0x240 drivers/net/wireguard/send.c:51
 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301
 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447
 kthread+0x346/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
Modules linked in:
---[ end trace acd066299e67bb58 ]---
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 be 08 c1 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 90 08 c1 fd 48 8b 1b 48 85 db 74 68
RSP: 0018:ffffc900010ef468 EFLAGS: 00010202

RAX: 000000000000005b RBX: 00000000000002d8 RCX: dffffc0000000000
RDX: ffff8881444493c0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900010ef4d8 R08: ffff8881444493c0 R09: 0000000000000003
R10: 0000000000000008 R11: 0000000000000000 R12: ffff888117410b00
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88811886cc90
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffd88f0000 CR3: 0000000121c97000 CR4: 00000000003506b0
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 be 08 c1 fd       	call   0xfdc108c8
   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 90 08 c1 fd       	call   0xfdc108c8
  38:	48 8b 1b             	mov    (%rbx),%rbx
  3b:	48 85 db             	test   %rbx,%rbx
  3e:	74 68                	je     0xa8

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/24 11:42 android13-5.10-lts ad9a98ef27a4 65d60d73 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in nexthop_get_nhc_lookup
2025/07/22 11:36 android13-5.10-lts ad9a98ef27a4 1555463b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in nexthop_get_nhc_lookup
2025/07/16 07:23 android13-5.10-lts 6de38b5f6c2b 124ec9cc .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in nexthop_get_nhc_lookup
2025/07/15 03:41 android13-5.10-lts d0d90e085c21 03fcfc4b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in nexthop_get_nhc_lookup
2025/07/11 17:31 android13-5.10-lts 59e9a7228857 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in nexthop_get_nhc_lookup
2025/07/10 02:48 android13-5.10-lts 59e9a7228857 956bd956 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in nexthop_get_nhc_lookup
2025/07/09 23:29 android13-5.10-lts 59e9a7228857 f4e5e155 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in nexthop_get_nhc_lookup
* Struck through repros no longer work on HEAD.