syzbot


general protection fault in __udp6_lib_lookup

Status: upstream: reported C repro on 2026/01/26 05:10
Reported-by: syzbot+375f9375a3c29c4d4e64@syzkaller.appspotmail.com
First crash: 7d18h, last: 7d07h

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc000000004e: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000270-0x0000000000000277]
CPU: 1 PID: 416 Comm: kworker/1:29 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: wg-crypt-wg0 wg_packet_tx_worker

RIP: 0010:bpf_sk_lookup_run_v6 include/linux/filter.h:1451 [inline]
RIP: 0010:udp6_lookup_run_bpf net/ipv6/udp.c:230 [inline]
RIP: 0010:__udp6_lib_lookup+0x5c6/0x860 net/ipv6/udp.c:267
Code: 3c 08 00 74 08 4c 89 ef e8 17 4f 9c fd 4d 8b 6d 00 b8 70 02 00 00 49 01 c5 4c 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 ef e8 ec 4e 9c fd 49 8b 5d 00 e8 13 7c 7a
RSP: 0018:ffffc90000170720 EFLAGS: 00010206

RAX: 000000000000004e RBX: ffffe8ffffd187a8 RCX: dffffc0000000000
RDX: 0000000080000102 RSI: ffffffff865ea838 RDI: ffffc900001707c0
RBP: ffffc90000170878 R08: ffffffff86e78048 R09: ffffffff86e78058
R10: ffffffff86e7805c R11: ffffffff86e78043 R12: ffff888112b87940
R13: 0000000000000270 R14: 0000000000000000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000100 CR3: 000000012940c000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __udp6_lib_lookup_skb+0xee/0x130 net/ipv6/udp.c:300
 __udp6_lib_rcv+0x765/0xe30 net/ipv6/udp.c:992
 udpv6_rcv+0x21/0x30 net/ipv6/udp.c:1098
 ip6_protocol_deliver_rcu+0x878/0x1340 net/ipv6/ip6_input.c:427
 ip6_input_finish net/ipv6/ip6_input.c:468 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip6_input+0xda/0x210 net/ipv6/ip6_input.c:477
 dst_input include/net/dst.h:461 [inline]
 ip6_rcv_finish+0x18c/0x360 net/ipv6/ip6_input.c:80
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ipv6_rcv+0xf0/0x230 net/ipv6/ip6_input.c:301
 __netif_receive_skb_one_core net/core/dev.c:5402 [inline]
 __netif_receive_skb+0xc8/0x280 net/core/dev.c:5516
 process_backlog+0x368/0x600 net/core/dev.c:6423
 napi_poll net/core/dev.c:6874 [inline]
 net_rx_action+0x44d/0xe00 net/core/dev.c:6944
 __do_softirq+0x255/0x563 kernel/softirq.c:309
 asm_call_irq_on_stack+0xf/0x20
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0x60/0x80 arch/x86/kernel/irq_64.c:77
 do_softirq+0xb0/0xf0 kernel/softirq.c:358
 __local_bh_enable_ip+0x70/0x80 kernel/softirq.c:194
 __raw_read_unlock_bh include/linux/rwlock_api_smp.h:251 [inline]
 _raw_read_unlock_bh+0x29/0x30 kernel/locking/spinlock.c:279
 wg_socket_send_skb_to_peer+0x172/0x1d0 drivers/net/wireguard/socket.c:184
 wg_packet_create_data_done drivers/net/wireguard/send.c:251 [inline]
 wg_packet_tx_worker+0x1b8/0x450 drivers/net/wireguard/send.c:276
 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301
 worker_thread+0xa6a/0x13c0 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 489377e03330ddff ]---
RIP: 0010:bpf_sk_lookup_run_v6 include/linux/filter.h:1451 [inline]
RIP: 0010:udp6_lookup_run_bpf net/ipv6/udp.c:230 [inline]
RIP: 0010:__udp6_lib_lookup+0x5c6/0x860 net/ipv6/udp.c:267
Code: 3c 08 00 74 08 4c 89 ef e8 17 4f 9c fd 4d 8b 6d 00 b8 70 02 00 00 49 01 c5 4c 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 ef e8 ec 4e 9c fd 49 8b 5d 00 e8 13 7c 7a
RSP: 0018:ffffc90000170720 EFLAGS: 00010206
RAX: 000000000000004e RBX: ffffe8ffffd187a8 RCX: dffffc0000000000
RDX: 0000000080000102 RSI: ffffffff865ea838 RDI: ffffc900001707c0
RBP: ffffc90000170878 R08: ffffffff86e78048 R09: ffffffff86e78058
R10: ffffffff86e7805c R11: ffffffff86e78043 R12: ffff888112b87940
R13: 0000000000000270 R14: 0000000000000000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000100 CR3: 000000012940c000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	3c 08                	cmp    $0x8,%al
   2:	00 74 08 4c          	add    %dh,0x4c(%rax,%rcx,1)
   6:	89 ef                	mov    %ebp,%edi
   8:	e8 17 4f 9c fd       	call   0xfd9c4f24
   d:	4d 8b 6d 00          	mov    0x0(%r13),%r13
  11:	b8 70 02 00 00       	mov    $0x270,%eax
  16:	49 01 c5             	add    %rax,%r13
  19:	4c 89 e8             	mov    %r13,%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:	4c 89 ef             	mov    %r13,%rdi
  33:	e8 ec 4e 9c fd       	call   0xfd9c4f24
  38:	49 8b 5d 00          	mov    0x0(%r13),%rbx
  3c:	e8                   	.byte 0xe8
  3d:	13                   	.byte 0x13
  3e:	7c 7a                	jl     0xba

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/26 09:00 android13-5.10-lts 5601baec60aa 55756628 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10-perf general protection fault in __udp6_lib_lookup
2026/01/26 05:07 android13-5.10-lts 5601baec60aa 55756628 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10-perf general protection fault in __udp6_lib_lookup
2026/01/25 21:53 android13-5.10-lts 5601baec60aa 55756628 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10-perf general protection fault in __udp6_lib_lookup
* Struck through repros no longer work on HEAD.