[syzbot] [bpf?] WARNING in __bpf_prog_ret0_warn

syzbot
2025-05-04T03:47:27Z

Hello,

syzbot found the following issue on:

HEAD commit: 8bac8898fe39 Merge tag 'mmc-v6.15-rc1' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10f03774580000
kernel config: https://syzkaller.appspot.com/x/.config?x=541aa584278da96c
dashboard link: https://syzkaller.appspot.com/bug?extid=0903f6d7f285e41cdf10
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1550ca70580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17d10f74580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-8bac8898.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5f7c2d7e1cd1/vmlinux-8bac8898.xz
kernel image: https://storage.googleapis.com/syzbot-assets/77a157d2769a/bzImage-8bac8898.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0903f6d7f285e41cdf10@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 3 PID: 217 at kernel/bpf/core.c:2357 __bpf_prog_ret0_warn+0xa/0x20 kernel/bpf/core.c:2357
Modules linked in:
CPU: 3 UID: 0 PID: 217 Comm: kworker/u32:6 Not tainted 6.15.0-rc4-syzkaller-00040-g8bac8898fe39 #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: ipv6_addrconf addrconf_dad_work
RIP: 0010:__bpf_prog_ret0_warn+0xa/0x20 kernel/bpf/core.c:2357
Code: f3 0f 1e fa e8 a7 c7 f0 ff 31 c0 c3 cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa e8 87 c7 f0 ff 90 <0f> 0b 90 31 c0 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90
RSP: 0018:ffffc900031f6c18 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffc9000006e000 RCX: 1ffff9200000dc06
RDX: ffff8880234ba440 RSI: ffffffff81ca6979 RDI: ffff888031e93040
RBP: ffffc900031f6cb8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88802b61e010
R13: ffff888031e93040 R14: 00000000000000a0 R15: ffff88802c3d4800
FS: 0000000000000000(0000) GS:ffff8880d6ce2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055557b6d2ca8 CR3: 000000002473e000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
bpf_dispatcher_nop_func include/linux/bpf.h:1316 [inline]
__bpf_prog_run include/linux/filter.h:718 [inline]
bpf_prog_run include/linux/filter.h:725 [inline]
cls_bpf_classify+0x74a/0x1110 net/sched/cls_bpf.c:105
tc_classify include/net/tc_wrapper.h:197 [inline]
__tcf_classify net/sched/cls_api.c:1764 [inline]
tcf_classify+0x7ef/0x1380 net/sched/cls_api.c:1860
htb_classify net/sched/sch_htb.c:245 [inline]
htb_enqueue+0x2f6/0x12d0 net/sched/sch_htb.c:624
dev_qdisc_enqueue net/core/dev.c:3984 [inline]
__dev_xmit_skb net/core/dev.c:4080 [inline]
__dev_queue_xmit+0x2142/0x43e0 net/core/dev.c:4595
dev_queue_xmit include/linux/netdevice.h:3350 [inline]
neigh_hh_output include/net/neighbour.h:523 [inline]
neigh_output include/net/neighbour.h:537 [inline]
ip_finish_output2+0xc38/0x21a0 net/ipv4/ip_output.c:235
__ip_finish_output net/ipv4/ip_output.c:313 [inline]
__ip_finish_output+0x49e/0x950 net/ipv4/ip_output.c:295
ip_finish_output+0x35/0x380 net/ipv4/ip_output.c:323
NF_HOOK_COND include/linux/netfilter.h:303 [inline]
ip_output+0x13b/0x2a0 net/ipv4/ip_output.c:433
dst_output include/net/dst.h:459 [inline]
ip_local_out+0x33e/0x4a0 net/ipv4/ip_output.c:129
iptunnel_xmit+0x5d5/0xa00 net/ipv4/ip_tunnel_core.c:82
geneve_xmit_skb drivers/net/geneve.c:921 [inline]
geneve_xmit+0x2bc5/0x5610 drivers/net/geneve.c:1046
__netdev_start_xmit include/linux/netdevice.h:5203 [inline]
netdev_start_xmit include/linux/netdevice.h:5212 [inline]
xmit_one net/core/dev.c:3776 [inline]
dev_hard_start_xmit+0x93/0x740 net/core/dev.c:3792
__dev_queue_xmit+0x7eb/0x43e0 net/core/dev.c:4629
dev_queue_xmit include/linux/netdevice.h:3350 [inline]
neigh_hh_output include/net/neighbour.h:523 [inline]
neigh_output include/net/neighbour.h:537 [inline]
ip6_finish_output2+0xe98/0x2020 net/ipv6/ip6_output.c:141
__ip6_finish_output net/ipv6/ip6_output.c:215 [inline]
ip6_finish_output+0x3f9/0x1360 net/ipv6/ip6_output.c:226
NF_HOOK_COND include/linux/netfilter.h:303 [inline]
ip6_output+0x1f9/0x540 net/ipv6/ip6_output.c:247
dst_output include/net/dst.h:459 [inline]
NF_HOOK include/linux/netfilter.h:314 [inline]
NF_HOOK include/linux/netfilter.h:308 [inline]
mld_sendpack+0x9e9/0x1220 net/ipv6/mcast.c:1868
mld_send_initial_cr.part.0+0x1a1/0x260 net/ipv6/mcast.c:2285
mld_send_initial_cr include/linux/refcount.h:291 [inline]
ipv6_mc_dad_complete+0x22c/0x2b0 net/ipv6/mcast.c:2293
addrconf_dad_completed+0xd8a/0x10d0 net/ipv6/addrconf.c:4341
addrconf_dad_work+0x84d/0x14e0 net/ipv6/addrconf.c:4269
process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
process_scheduled_works kernel/workqueue.c:3319 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
kthread+0x3c2/0x780 kernel/kthread.c:464
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>

---
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