CVE-2025-71098

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

ip6_gre: make ip6gre_header() robust

Over the years, syzbot found many ways to crash the kernel

in ip6gre_header() [1].

This involves team or bonding drivers ability to dynamically

change their dev->needed_headroom and/or dev->hard_header_len

In this particular crash mld_newpack() allocated an skb

with a too small reserve/headroom, and by the time mld_sendpack()

was called, syzbot managed to attach an ip6gre device.

[1]

skbuff: skb_under_panic: text:ffffffff8a1d69a8 len:136 put:40 head:ffff888059bc7000 data:ffff888059bc6fe8 tail:0x70 end:0x6c0 dev:team0

------------[ cut here ]------------

kernel BUG at net/core/skbuff.c:213 !

<TASK>

skb_under_panic net/core/skbuff.c:223 [inline]

skb_push+0xc3/0xe0 net/core/skbuff.c:2641

ip6gre_header+0xc8/0x790 net/ipv6/ip6_gre.c:1371

dev_hard_header include/linux/netdevice.h:3436 [inline]

neigh_connected_output+0x286/0x460 net/core/neighbour.c:1618

neigh_output inc

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References