CVE-2026-68127ila: reload IPv6 header after pskb_may_pull in checksum adjust

Official description

In the Linux kernel, the following vulnerability has been resolved: ila: reload IPv6 header after pskb_may_pull in checksum adjust ila_csum_adjust_transport() caches ip6h = ipv6_hdr(skb) before calling pskb_may_pull(). On a non-linear skb whose transport header sits in a page fragment, pskb_may_pull() can call __pskb_pull_tail() / pskb_expand_head() and free the old skb head, leaving ip6h dangling; the following get_csum_diff(ip6h, p) then reads freed memory. ila_update_ipv6_locator() uses ip6h (and the iaddr derived from it) again after the csum-adjust call and additionally writes the new locator through that pointer. Impact: a remote IPv6 packet routed through a configured ILA csum-adjust-transport route or receive-side mapping triggers a slab-use-after-free in ila_update_ipv6_locator() (KASAN). The route or mapping requires CAP_NET_ADMIN to configure, but trigger packets are unauthenticated once it exists. Reload ip6h after each pskb_may_pull() in ila_csum_adjust_transport() before the csum-diff read. In ila_update_ipv6_locator() only the ILA_CSUM_ADJUST_TRANSPORT case pulls the skb, so reload ip6h and iaddr in that case alone before the destination-address write; the neutral-map modes never pull and keep their cached pointers.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/e451a904606c571f731ef7a06b3398619dce5300
• https://git.kernel.org/stable/c/1eadcb43893b897ade85ac5bf5c618054bc3c655
• https://git.kernel.org/stable/c/ba353caafb06ccee57b78d3254e3cebf1dea4a93
• https://git.kernel.org/stable/c/896a9512d0d83c2a4b357e5585b7b62a8e3f95c1
• https://git.kernel.org/stable/c/7097a0280b178237265681be66d1bef11d15894b
• https://git.kernel.org/stable/c/472aba2603ca74c4f7722cb0c0296942b0776b8d
• https://git.kernel.org/stable/c/c6a13ae00dab3a1a8c7cf2f843f0fc9e8d4b0ccc
• https://git.kernel.org/stable/c/92d3817649df2b0b6a008a686c8275c88d7ef594