CVE-2024-49979

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net: gso: fix tcp fraglist segmentation after pull from frag_list<br /> <br /> Detect tcp gso fraglist skbs with corrupted geometry (see below) and<br /> pass these to skb_segment instead of skb_segment_list, as the first<br /> can segment them correctly.<br /> <br /> Valid SKB_GSO_FRAGLIST skbs<br /> - consist of two or more segments<br /> - the head_skb holds the protocol headers plus first gso_size<br /> - one or more frag_list skbs hold exactly one segment<br /> - all but the last must be gso_size<br /> <br /> Optional datapath hooks such as NAT and BPF (bpf_skb_pull_data) can<br /> modify these skbs, breaking these invariants.<br /> <br /> In extreme cases they pull all data into skb linear. For TCP, this<br /> causes a NULL ptr deref in __tcpv4_gso_segment_list_csum at<br /> tcp_hdr(seg-&gt;next).<br /> <br /> Detect invalid geometry due to pull, by checking head_skb size.<br /> Don&amp;#39;t just drop, as this may blackhole a destination. Convert to be<br /> able to pass to regular skb_segment.<br /> <br /> Approach and description based on a patch by Willem de Bruijn.