CVE-2026-53091: Incorrect Calculation of Buffer Size

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

net: pull headers in qdisc_pkt_len_segs_init()

Most ndo_start_xmit() methods expects headers of gso packets to be already in skb->head.

net/core/tso.c users are particularly at risk, because tso_build_hdr() does a memcpy(hdr, skb->data, hdr_len);

qdisc_pkt_len_segs_init() already does a dissection of gso packets.

Use pskb_may_pull() instead of skb_header_pointer() to make sure drivers do not have to reimplement this.

Some malicious packets could be fed, detect them so that we can drop them sooner with a new SKB_DROP_REASON_SKB_BAD_GSO drop_reason.