Re: [syzbot] [net?] general protection fault in veth_xdp_rcv

From: Ihor Solodrai
Date: Mon Jun 09 2025 - 16:55:44 EST

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On 6/2/25 6:21 AM, syzbot wrote:

Hello,

syzbot found the following issue on:

HEAD commit: 4cb6c8af8591 selftests/filesystems: Fix build of anon_inod..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11e8300c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=5319177d225a42f1
dashboard link: https://syzkaller.appspot.com/bug?extid=c4c7bf27f6b0c4bd97fe
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-4cb6c8af.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bc0e5dfdd686/vmlinux-4cb6c8af.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2cdd323de6ca/bzImage-4cb6c8af.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c4c7bf27f6b0c4bd97fe@xxxxxxxxxxxxxxxxxxxxxxxxx

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000098: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x00000000000004c0-0x00000000000004c7]
CPU: 1 UID: 0 PID: 5975 Comm: kworker/1:4 Not tainted 6.15.0-syzkaller-10402-g4cb6c8af8591 #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: wg-kex-wg0 wg_packet_handshake_receive_worker
RIP: 0010:netdev_get_tx_queue include/linux/netdevice.h:2636 [inline]
RIP: 0010:veth_xdp_rcv.constprop.0+0x142/0xda0 drivers/net/veth.c:912
Code: 54 d9 31 fb 45 85 e4 0f 85 db 08 00 00 e8 06 de 31 fb 48 8d bd c0 04 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 18 0c 00 00 44 8b a5 c0 04 00
RSP: 0018:ffffc900006a09b8 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff868a1686
RDX: 0000000000000098 RSI: ffffffff868a0d9a RDI: 00000000000004c0
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: ffffc900006a0ff8 R12: 0000000000000001
R13: 1ffff920000d4145 R14: ffffc900006a0e58 R15: ffff8880503d0000
FS: 0000000000000000(0000) GS:ffff8880d686e000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe5e3a6ad58 CR3: 000000000e382000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
veth_poll+0x19c/0x9c0 drivers/net/veth.c:979
__napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7414
napi_poll net/core/dev.c:7478 [inline]
net_rx_action+0xa9f/0xfe0 net/core/dev.c:7605
handle_softirqs+0x219/0x8e0 kernel/softirq.c:579
do_softirq kernel/softirq.c:480 [inline]
do_softirq+0xb2/0xf0 kernel/softirq.c:467
</IRQ>
<TASK>
__local_bh_enable_ip+0x100/0x120 kernel/softirq.c:407
local_bh_enable include/linux/bottom_half.h:33 [inline]
fpregs_unlock arch/x86/include/asm/fpu/api.h:77 [inline]
kernel_fpu_end+0x5e/0x70 arch/x86/kernel/fpu/core.c:476
blake2s_compress+0x7f/0xe0 arch/x86/lib/crypto/blake2s-glue.c:46
blake2s_final+0xc9/0x150 lib/crypto/blake2s.c:54
hmac.constprop.0+0x335/0x420 drivers/net/wireguard/noise.c:333
kdf.constprop.0+0x122/0x280 drivers/net/wireguard/noise.c:360
mix_dh+0xe8/0x150 drivers/net/wireguard/noise.c:413
wg_noise_handshake_consume_initiation+0x265/0x880 drivers/net/wireguard/noise.c:608
wg_receive_handshake_packet+0x219/0xbf0 drivers/net/wireguard/receive.c:144
wg_packet_handshake_receive_worker+0x17f/0x3a0 drivers/net/wireguard/receive.c:213
process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
process_scheduled_works kernel/workqueue.c:3321 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
kthread+0x3c2/0x780 kernel/kthread.c:464
ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:netdev_get_tx_queue include/linux/netdevice.h:2636 [inline]
RIP: 0010:veth_xdp_rcv.constprop.0+0x142/0xda0 drivers/net/veth.c:912
Code: 54 d9 31 fb 45 85 e4 0f 85 db 08 00 00 e8 06 de 31 fb 48 8d bd c0 04 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 18 0c 00 00 44 8b a5 c0 04 00
RSP: 0018:ffffc900006a09b8 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff868a1686
RDX: 0000000000000098 RSI: ffffffff868a0d9a RDI: 00000000000004c0
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: ffffc900006a0ff8 R12: 0000000000000001
R13: 1ffff920000d4145 R14: ffffc900006a0e58 R15: ffff8880503d0000
FS: 0000000000000000(0000) GS:ffff8880d686e000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe5e3a6ad58 CR3: 000000000e382000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------

Got a very similar call trace on current bpf-next (e41079f53e87) [1],
see a paste below. It's flaky, couldn't reproduce so far.

Any relevant fixes in flight?

#629/1 xdp_veth_broadcast_redirect/0/BROADCAST:OK
#629/2 xdp_veth_broadcast_redirect/0/(BROADCAST | EXCLUDE_INGRESS):OK
#629/3 xdp_veth_broadcast_redirect/DRV_MODE/BROADCAST:OK
#629/4 xdp_veth_broadcast_redirect/DRV_MODE/(BROADCAST | EXCLUDE_INGRESS):OK
#629/5 xdp_veth_broadcast_redirect/SKB_MODE/BROADCAST:OK
#629/6 xdp_veth_broadcast_redirect/SKB_MODE/(BROADCAST | EXCLUDE_INGRESS):OK
#629 xdp_veth_broadcast_redirect:OK
[ 343.217465] BUG: kernel NULL pointer dereference, address: 0000000000000018
[ 343.218173] #PF: supervisor read access in kernel mode
[ 343.218644] #PF: error_code(0x0000) - not-present page
[ 343.219128] PGD 0 P4D 0
[ 343.219379] Oops: Oops: 0000 [#1] SMP NOPTI
[ 343.219768] CPU: 1 UID: 0 PID: 7635 Comm: kworker/1:11 Tainted: G W OE 6.15.0-g2b36f2252b0a-dirty #7 PREEMPT(full)
[ 343.220844] Tainted: [W]=WARN, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
[ 343.221436] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 343.222356] Workqueue: mld mld_dad_work
[ 343.222730] RIP: 0010:veth_xdp_rcv.constprop.0+0x6b/0x380
[ 343.223242] Code: 01 48 89 84 24 90 00 00 00 31 c0 48 8b aa 80 0c 00 00 f3 48 ab e8 f5 e3 48 00 85 c0 0f 85 9c 02 00 00 4c 8d 34 5b 49 c1 e6 07 <4c> 03 75 18 45 85 e4 0f 8e ec 02 00 00 31 db 31 ed eb 4c 48 83 e6
[ 343.224977] RSP: 0018:ffff9aaa400e8ca8 EFLAGS: 00010246
[ 343.225475] RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000002
[ 343.226139] RDX: 0000000000000001 RSI: ffff8f22912a5000 RDI: ffff9aaa400e8d38
[ 343.226808] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
[ 343.227484] R10: 0000000000000001 R11: ffff9aaa400e8ff8 R12: 0000000000000040
[ 343.228143] R13: ffff9aaa400e8d78 R14: 0000000000000000 R15: ffff8f220ad0f000
[ 343.228820] FS: 0000000000000000(0000) GS:ffff8f22912a5000(0000) knlGS:0000000000000000
[ 343.229572] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 343.230118] CR2: 0000000000000018 CR3: 000000010ce45005 CR4: 0000000000770ef0
[ 343.230794] PKRU: 55555554
[ 343.231061] Call Trace:
[ 343.231306] <IRQ>
[ 343.231522] veth_poll+0x7b/0x3a0
[ 343.231856] __napi_poll.constprop.0+0x28/0x1d0
[ 343.232297] net_rx_action+0x199/0x350
[ 343.232682] handle_softirqs+0xd3/0x400
[ 343.233057] ? __dev_queue_xmit+0x27b/0x1250
[ 343.233473] do_softirq+0x43/0x90
[ 343.233804] </IRQ>
[ 343.234016] <TASK>
[ 343.234226] __local_bh_enable_ip+0xb5/0xd0
[ 343.234622] ? __dev_queue_xmit+0x27b/0x1250
[ 343.235035] __dev_queue_xmit+0x290/0x1250
[ 343.235431] ? lock_acquire+0xbe/0x2c0
[ 343.235797] ? ip6_finish_output+0x25e/0x540
[ 343.236210] ? mark_held_locks+0x40/0x70
[ 343.236583] ip6_finish_output2+0x38f/0xb80
[ 343.237002] ? lock_release+0xc6/0x290
[ 343.237364] ip6_finish_output+0x25e/0x540
[ 343.237761] mld_sendpack+0x1c1/0x3a0
[ 343.238123] mld_dad_work+0x3e/0x150
[ 343.238473] process_one_work+0x1f8/0x580
[ 343.238859] worker_thread+0x1ce/0x3c0
[ 343.239224] ? __pfx_worker_thread+0x10/0x10
[ 343.239638] kthread+0x128/0x250
[ 343.239954] ? __pfx_kthread+0x10/0x10
[ 343.240320] ? __pfx_kthread+0x10/0x10
[ 343.240691] ret_from_fork+0x15c/0x1b0
[ 343.241056] ? __pfx_kthread+0x10/0x10
[ 343.241418] ret_from_fork_asm+0x1a/0x30
[ 343.241800] </TASK>
[ 343.242021] Modules linked in: bpf_testmod(OE) [last unloaded: bpf_test_no_cfi(OE)]
[ 343.242737] CR2: 0000000000000018
[ 343.243064] ---[ end trace 0000000000000000 ]---
[ 343.243503] RIP: 0010:veth_xdp_rcv.constprop.0+0x6b/0x380
[ 343.244014] Code: 01 48 89 84 24 90 00 00 00 31 c0 48 8b aa 80 0c 00 00 f3 48 ab e8 f5 e3 48 00 85 c0 0f 85 9c 02 00 00 4c 8d 34 5b 49 c1 e6 07 <4c> 03 75 18 45 85 e4 0f 8e ec 02 00 00 31 db 31 ed eb 4c 48 83 e6
[ 343.245743] RSP: 0018:ffff9aaa400e8ca8 EFLAGS: 00010246
[ 343.246236] RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000002
[ 343.246897] RDX: 0000000000000001 RSI: ffff8f22912a5000 RDI: ffff9aaa400e8d38
[ 343.247557] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
[ 343.248219] R10: 0000000000000001 R11: ffff9aaa400e8ff8 R12: 0000000000000040
[ 343.248868] R13: ffff9aaa400e8d78 R14: 0000000000000000 R15: ffff8f220ad0f000
[ 343.249496] FS: 0000000000000000(0000) GS:ffff8f22912a5000(0000) knlGS:0000000000000000
[ 343.250109] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 343.250651] CR2: 0000000000000018 CR3: 000000010ce45005 CR4: 0000000000770ef0
[ 343.251320] PKRU: 55555554
[ 343.251548] Kernel panic - not syncing: Fatal exception in interrupt
[ 343.252317] Kernel Offset: 0x27000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
Failed to run command

Caused by:
0: Failed to QGA guest-exec-status
1: error running guest_exec_status
2: Broken pipe (os error 32)
3: Broken pipe (os error 32)
##[error]Process completed with exit code 2.

[1] https://github.com/kernel-patches/bpf/actions/runs/15543380196/job/43759847203

Code disassembly (best guess):
0: 54 push %rsp
1: d9 31 fnstenv (%rcx)
3: fb sti
4: 45 85 e4 test %r12d,%r12d
7: 0f 85 db 08 00 00 jne 0x8e8
d: e8 06 de 31 fb call 0xfb31de18
12: 48 8d bd c0 04 00 00 lea 0x4c0(%rbp),%rdi
19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
20: fc ff df
23: 48 89 fa mov %rdi,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 0f b6 04 02 movzbl (%rdx,%rax,1),%eax <-- trapping instruction
2e: 84 c0 test %al,%al
30: 74 08 je 0x3a
32: 3c 03 cmp $0x3,%al
34: 0f 8e 18 0c 00 00 jle 0xc52
3a: 44 rex.R
3b: 8b .byte 0x8b
3c: a5 movsl %ds:(%rsi),%es:(%rdi)
3d: c0 .byte 0xc0
3e: 04 00 add $0x0,%al

---
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