CVE-2026-43036

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

net: use skbheaderpointer() for TCPv4 GSO frag_off check

Syzbot reported a KMSAN uninit-value warning in gsofeaturescheck() called from netifskbfeatures() [1].

gsofeaturescheck() reads iph->fragoff to decide whether to clear mangleidfeatures. Accessing the IPv4 header via iphdr()/inneriphdr() can rely on skb header offsets that are not always safe for direct dereference on packets injected from PFPACKET paths.

Use skbheaderpointer() for the TCPv4 frag_off check so the header read is robust whether data is already linear or needs copying.

[1] https://syzkaller.appspot.com/bug?extid=1543a7d954d9c6d00407