linux-kernel - [syzbot ci] Re: vrf: Drop existing dst reference in vrf_ip6_input

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Message-ID: <6880a6cf.050a0220.40ccf.0000.GAE@google.com>
Date: Wed, 23 Jul 2025 02:09:35 -0700
From: syzbot ci <syzbot+ci7bed65dd2de1adbd@...kaller.appspotmail.com>
To: andrew@...n.ch, davem@...emloft.net, dsahern@...nel.org, 
	edumazet@...gle.com, horms@...nel.org, kuba@...nel.org, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, pabeni@...hat.com, 
	sdf@...ichev.me
Cc: syzbot@...ts.linux.dev
Subject: [syzbot ci] Re: vrf: Drop existing dst reference in vrf_ip6_input_dst

syzbot ci has tested the following series

[v1] vrf: Drop existing dst reference in vrf_ip6_input_dst
https://lore.kernel.org/all/<20250722210256.143208-1-sdf@...ichev.me>
* [PATCH net 1/2] vrf: Drop existing dst reference in vrf_ip6_input_dst
* [PATCH net 2/2] net: Warn when overriding referenced dst entry

and found the following issue:
WARNING in nf_reject_fill_skb_dst

Full report is available here:
https://ci.syzbot.org/series/c92e1af5-3b8b-4c26-8104-acca93ad8939

***

WARNING in nf_reject_fill_skb_dst

tree:      net
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/netdev/net.git
base:      cf074eca0065bc5142e6004ae236bb35a2687fdf
arch:      amd64
compiler:  Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
config:    https://ci.syzbot.org/builds/235c4af3-77ea-4670-9c9e-9de1ef0a5aa6/config
syz repro: https://ci.syzbot.org/findings/1038832f-72d8-4491-9ac9-28339d31f0f7/syz_repro

------------[ cut here ]------------
WARNING: CPU: 1 PID: 12 at ./include/linux/skbuff.h:1165 nf_reject_fill_skb_dst+0x313/0x3b0
Modules linked in:
CPU: 1 UID: 0 PID: 12 Comm: kworker/u8:0 Not tainted 6.16.0-rc6-syzkaller-00135-gcf074eca0065-dirty #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: ipv6_addrconf addrconf_dad_work
RIP: 0010:nf_reject_fill_skb_dst+0x313/0x3b0
Code: 8b 0d f1 35 98 08 48 3b 8c 24 e0 00 00 00 75 6b 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d e9 54 19 69 01 cc e8 9e 7e b8 f7 90 <0f> 0b 90 e9 43 ff ff ff e8 90 7e b8 f7 90 0f 0b 90 e9 e3 fe ff ff
RSP: 0018:ffffc900001e0360 EFLAGS: 00010246
RAX: ffffffff8a07aa52 RBX: ffff888110f75500 RCX: ffff88801c2f5640
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900001e0490 R08: ffffffff8fa1d6f7 R09: 1ffffffff1f43ade
R10: dffffc0000000000 R11: fffffbfff1f43adf R12: ffff888110f75501
R13: dffffc0000000001 R14: 1ffff9200003c070 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881a3c22000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000000c0 CR3: 000000001ff6e000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 nf_send_unreach+0x17b/0x700
 nft_reject_inet_eval+0x4bc/0x690
 nft_do_chain+0x40c/0x1920
 nft_do_chain_inet+0x25d/0x340
 nf_hook_slow+0xc5/0x220
 NF_HOOK+0x206/0x3a0
 __netif_receive_skb+0x143/0x380
 process_backlog+0x60e/0x14f0
 __napi_poll+0xc7/0x480
 net_rx_action+0x707/0xe30
 handle_softirqs+0x286/0x870
 do_softirq+0xec/0x180
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x17d/0x1c0
 __dev_queue_xmit+0x1cd7/0x3a70
 ip6_finish_output2+0x11fe/0x16a0
 ndisc_send_skb+0xc77/0x1500
 ndisc_send_ns+0xcb/0x150
 addrconf_dad_work+0xaae/0x14b0
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>


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This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@...glegroups.com.