[syzbot ci] Re: net: tunnel: fix stale transport header after GRE/TEB decap

[syzbot ci]

syzbot ci has tested the following series

[v1] net: tunnel: fix stale transport header after GRE/TEB decap
https://lore.kernel.org/all/20260416034610.8873-1-jiayuan.chen@xxxxxxxxx
* [PATCH net v1 1/2] net: tunnel: fix stale transport header after GRE/TEB decap
* [PATCH net-next v1 2/2] net: add DEBUG_NET_WARN_ON_ONCE for negative transport offset

and found the following issue:
WARNING in udpv6_err

Full report is available here:
https://ci.syzbot.org/series/3886f2f1-a6d5-4c5c-8dc8-bc1cec577567

***

WARNING in udpv6_err

tree:      net
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/netdev/net.git
base:      1f5ffc672165ff851063a5fd044b727ab2517ae3
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/06cf41a2-60fe-4f9b-8f68-57eb6d1e48cc/config

------------[ cut here ]------------
off < 0
WARNING: ./include/linux/skbuff.h:3239 at udpv6_err+0x1521/0x16d0, CPU#0: kworker/u9:2/51
Modules linked in:

CPU: 0 UID: 0 PID: 51 Comm: kworker/u9:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: wg-kex-wg0 wg_packet_handshake_send_worker

RIP: 0010:udpv6_err+0x1521/0x16d0
Code: f7 b0 01 89 44 24 30 49 bf 00 00 00 00 00 fc ff df e9 ea ef ff ff e8 8e f2 66 f7 90 0f 0b 90 e9 2a f9 ff ff e8 80 f2 66 f7 90 <0f> 0b 90 e9 bb f9 ff ff e8 72 f2 66 f7 90 0f 0b 90 e9 1a fa ff ff
RSP: 0018:ffffc900000074e0 EFLAGS: 00010246

RAX: ffffffff8a5e6c30 RBX: 0000000080000000 RCX: ffff888106e91d80
RDX: 0000000000000100 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc90000007670 R08: ffff88810be30ae0 R09: 000000000000234e
R10: 000000000000003c R11: ffffffff8a5e5710 R12: ffff888116513390
R13: ffff888114c38900 R14: fffffffffffffff8 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff88818dc43000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555561513898 CR3: 000000016fad2000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 icmpv6_notify+0x407/0x850
 icmpv6_rcv+0x13b0/0x1d80
 ip6_protocol_deliver_rcu+0xe37/0x1610
 ip6_input_finish+0x191/0x370
 NF_HOOK+0x336/0x3c0
 ip6_input+0x16a/0x270
 NF_HOOK+0x336/0x3c0
 process_backlog+0x7dd/0x1950
 __napi_poll+0xae/0x340
 net_rx_action+0x627/0xf70
 handle_softirqs+0x22a/0x840
 do_softirq+0x76/0xd0
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0xf8/0x130
 wg_socket_send_skb_to_peer+0x16b/0x1d0
 wg_packet_handshake_send_worker+0x203/0x350
 process_scheduled_works+0xb5d/0x1860


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@xxxxxxxxxxxxxxxxxxxxxxxxx

---
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