[moderation/CI] Re: ip: validate options before echoing them

[syzbot ci <syzbot+ci580e1d9fe98861cc@syzkaller.appspotmail.com>]

syzbot ci has tested the following series

[v3] ip: validate options before echoing them
https://lore.kernel.org/all/20260902055802.3724915-1-4ncienth@gmail.com
* [PATCH net v3] ip: validate options before echoing them

and found the following issue:
WARNING in __ip_options_echo

Full report is available here:
https://ci.syzbot.org/series/58d17295-c695-49b2-826d-b0fe305808e9

***

WARNING in __ip_options_echo

tree:      linux-next
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next
base:      70f3995830d3f1e79faa14eb0605914f778feca9
arch:      amd64
compiler:  Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
config:    https://ci.syzbot.org/builds/9a250d6c-0a45-4565-bbc0-cac6bc3e42ee/config
syz repro: https://ci.syzbot.org/findings/5fa937c9-0c72-4a82-8221-cd01d8dc83d5/syz_repro

------------[ cut here ]------------
len > ((int)(~0U >> 1))
WARNING: ./include/linux/skbuff.h:2864 at pskb_may_pull_reason include/linux/skbuff.h:2864 [inline], CPU#1: syz.0.17/5791
WARNING: ./include/linux/skbuff.h:2864 at pskb_network_may_pull_reason include/linux/skbuff.h:3294 [inline], CPU#1: syz.0.17/5791
WARNING: ./include/linux/skbuff.h:2864 at pskb_network_may_pull include/linux/skbuff.h:3299 [inline], CPU#1: syz.0.17/5791
WARNING: ./include/linux/skbuff.h:2864 at __ip_options_echo+0x10e4/0x1870 net/ipv4/ip_options.c:115, CPU#1: syz.0.17/5791
Modules linked in:
CPU: 1 UID: 0 PID: 5791 Comm: syz.0.17 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:pskb_may_pull_reason include/linux/skbuff.h:2864 [inline]
RIP: 0010:pskb_network_may_pull_reason include/linux/skbuff.h:3294 [inline]
RIP: 0010:pskb_network_may_pull include/linux/skbuff.h:3299 [inline]
RIP: 0010:__ip_options_echo+0x10e4/0x1870 net/ipv4/ip_options.c:115
Code: 00 00 00 fc ff df 43 0f b6 04 3c 84 c0 0f 85 64 07 00 00 41 88 1e 4c 8b 64 24 10 41 83 c4 04 e9 a7 fe ff ff e8 7d 13 84 f7 90 <0f> 0b 90 e9 35 f1 ff ff 44 89 e7 44 89 f6 e8 79 15 84 f7 45 39 f4
RSP: 0018:ffffc90004efef40 EFLAGS: 00010293
RAX: ffffffff8a43a023 RBX: ffff8881b89a6b58 RCX: ffff888111125a00
RDX: 0000000000000000 RSI: 00000000fffffff8 RDI: 0000000000000000
RBP: ffffc90004eff070 R08: ffffc90004eff2c7 R09: 0000000000000000
R10: ffffc90004eff2b8 R11: fffff520009dfe59 R12: 00000000fffffff8
R13: ffff8881b89a6a80 R14: ffff8881b89a6b00 R15: 000000000000001c
FS:  00007f39f8af86c0(0000) GS:ffff8882a8cdf000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f39f8af7ff8 CR3: 0000000112830000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 ip_options_echo include/net/ip.h:798 [inline]
 icmp_reply+0x2da/0xc90 net/ipv4/icmp.c:429
 icmp_timestamp+0x246/0x370 net/ipv4/icmp.c:1430
 icmp_rcv+0xd33/0x1290 net/ipv4/icmp.c:1543
 ip_protocol_deliver_rcu+0x2dc/0x440 net/ipv4/ip_input.c:207
 ip_local_deliver_finish+0x3bb/0x6f0 net/ipv4/ip_input.c:241
 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:325
 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:325
 __netif_receive_skb_one_core net/core/dev.c:6264 [inline]
 __netif_receive_skb net/core/dev.c:6377 [inline]
 netif_receive_skb_internal net/core/dev.c:6463 [inline]
 netif_receive_skb+0x45b/0xbf0 net/core/dev.c:6522
 tun_rx_batched+0x1de/0x790 drivers/net/tun.c:1571
 tun_get_user+0x2be0/0x44d0 drivers/net/tun.c:2045
 tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:2091
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f39f7b5e98e
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:00007f39f8af7fb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f39f8af86c0 RCX: 00007f39f7b5e98e
RDX: 000000000000003e RSI: 0000200000000780 RDI: 00000000000000c8
RBP: 00007f39f7c35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f39f7e26038 R14: 00007f39f7e25fa0 R15: 00007fff66b2b028
 </TASK>


***

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---
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