CVE-2025-38572ipv6: reject malicious packets in ipv6_gso_segment()

Official description

In the Linux kernel, the following vulnerability has been resolved: ipv6: reject malicious packets in ipv6_gso_segment() syzbot was able to craft a packet with very long IPv6 extension headers leading to an overflow of skb->transport_header. This 16bit field has a limited range. Add skb_reset_transport_header_careful() helper and use it from ipv6_gso_segment() WARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 skb_reset_transport_header include/linux/skbuff.h:3032 [inline] WARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151 Modules linked in: CPU: 0 UID: 0 PID: 5871 Comm: syz-executor211 Not tainted 6.16.0-rc6-syzkaller-g7abc678e3084 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:skb_reset_transport_header include/linux/skbuff.h:3032 [inline] RIP: 0010:ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151 Call Trace: <TASK> skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53 nsh_gso_segment+0x54a/0xe10 net/nsh/nsh.c:110 skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53 __skb_gso_segment+0x342/0x510 net/core/gso.c:124 skb_gso_segment include/net/gso.h:83 [inline] validate_xmit_skb+0x857/0x11b0 net/core/dev.c:3950 validate_xmit_skb_list+0x84/0x120 net/core/dev.c:4000 sch_direct_xmit+0xd3/0x4b0 net/sched/sch_generic.c:329 __dev_xmit_skb net/core/dev.c:4102 [inline] __dev_queue_xmit+0x17b6/0x3a70 net/core/dev.c:4679

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/5dc60b2a00ed7629214ac0c48e43f40af2078703
• https://git.kernel.org/stable/c/3f638e0b28bde7c3354a0df938ab3a96739455d1
• https://git.kernel.org/stable/c/09ff062b89d8e48165247d677d1ca23d6d607e9b
• https://git.kernel.org/stable/c/de322cdf600fc9433845a9e944d1ca6b31cfb67e
• https://git.kernel.org/stable/c/ef05007b403dcc21e701cb1f30d4572ac0a9da20
• https://git.kernel.org/stable/c/5489e7fc6f8be3062f8cb7e49406de4bfd94db67
• https://git.kernel.org/stable/c/573b8250fc2554761db3bc2bbdbab23789d52d4e
• https://git.kernel.org/stable/c/ee851768e4b8371ce151fd446d24bf3ae2d18789
• https://git.kernel.org/stable/c/d45cf1e7d7180256e17c9ce88e32e8061a7887fe
• https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
• https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html