[syzbot ci] Re: xfrm: fix IPv6 atomic fragment policy handling

[syzbot ci <syzbot+ci38d3d40fc327a9e2@syzkaller.appspotmail.com>]

syzbot ci has tested the following series

[v3] xfrm: fix IPv6 atomic fragment policy handling
https://lore.kernel.org/all/20261106202910.723098-2-Jeremy.Jean@oss.cyber.gouv.fr
* [PATCH net v3 1/2] xfrm: fix IPv6 first-fragment protocol decode
* [PATCH net v3 2/2] xfrm: fix selector matching for IPv6 atomic fragments

and found the following issue:
WARNING in __xfrm_decode_session

Full report is available here:
https://ci.syzbot.org/series/9d92ff08-0b82-4440-b345-9628353f5181

***

WARNING in __xfrm_decode_session

tree:      net
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/netdev/net.git
base:      2d2200551ccc3b9e444aecb59c4b53287e169266
arch:      amd64
compiler:  Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
config:    https://ci.syzbot.org/builds/fe2ead38-2a3d-497a-9bae-e5da0ee59933/config

------------[ cut here ]------------
len > ((int)(~0U >> 1))
WARNING: ./include/linux/skbuff.h:2856 at __xfrm_decode_session+0xafb/0xed0, CPU#0: syz.0.121/6184
Modules linked in:
CPU: 0 UID: 0 PID: 6184 Comm: syz.0.121 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
RIP: 0010:__xfrm_decode_session+0xafb/0xed0
Code: bf e0 00 00 00 4d 03 3e 4c 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 11 03 00 00 45 8b 37 e9 33 fd ff ff e8 c6 c7 30 f7 90 <0f> 0b 90 e9 8c f7 ff ff 44 89 ef 8b 5c 24 20 89 de e8 bf c9 30 f7
RSP: 0018:ffffc9000e926b60 EFLAGS: 00010283
RAX: ffffffff8a9849aa RBX: 1ffff92001d24d74 RCX: 0000000000080000
RDX: ffffc90006ec1000 RSI: 0000000000000c7f RDI: 0000000000000c80
RBP: ffffc9000e926c90 R08: ffff88816dd8bc00 R09: 0000000000000002
R10: 000000000000000a R11: 0000000000000002 R12: ffffc9000e926bc0
R13: 00000000fffffff8 R14: ffff888105f226d8 R15: dffffc0000000000
FS:  00007fc136da96c0(0000) GS:ffff88818be0d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000002cc0 CR3: 000000017256e000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 icmpv6_route_lookup+0x44a/0x610
 icmp6_send+0x114c/0x1b50
 icmpv6_param_prob_reason+0x32/0x50
 ipv6_frag_rcv+0x927/0x2b40
 ip6_protocol_deliver_rcu+0xe8c/0x1680
 ip6_input_finish+0x191/0x370
 NF_HOOK+0x336/0x3c0
 ip6_input+0x16a/0x270
 NF_HOOK+0x336/0x3c0
 netif_receive_skb+0x278/0xbf0
 tun_rx_batched+0x1de/0x790
 tun_get_user+0x2b78/0x4470
 tun_chr_write_iter+0x113/0x200
 vfs_write+0x612/0xba0
 ksys_write+0x150/0x270
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc135f6974e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007fc136da8fb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc136da96c0 RCX: 00007fc135f6974e
RDX: 000000000000004a RSI: 0000200000000700 RDI: 00000000000000c8
RBP: 00007fc136037f6d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc136226038 R14: 00007fc136225fa0 R15: 00007ffcfeaad798
 </TASK>


***

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@syzkaller.appspotmail.com

---
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