CVE-2024-49979

Summary

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

net: gso: fix tcp fraglist segmentation after pull from frag_list

Detect tcp gso fraglist skbs with corrupted geometry (see below) and pass these to skb_segment instead of skb_segment_list, as the first can segment them correctly.

Valid SKB_GSO_FRAGLIST skbs

  • consist of two or more segments
  • the head_skb holds the protocol headers plus first gso_size
  • one or more frag_list skbs hold exactly one segment
  • all but the last must be gso_size

Optional datapath hooks such as NAT and BPF (bpf_skb_pull_data) can modify these skbs, breaking these invariants.

In extreme cases they pull all data into skb linear. For TCP, this causes a NULL ptr deref in __tcpv4_gso_segment_list_csum at tcp_hdr(seg->next).

Detect invalid geometry due to pull, by checking head_skb size. Don't just drop, as this may blackhole a destination. Convert to be able to pass to regular skb_segment.

Approach and description based on a patch by Willem de Bruijn.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxc2ea8cab368b9f25b5937a7f07ab1a66e90b8064 < 75733986fcb0725c0033cde94764389e287b331eaffected
LinuxLinux1f2b859225eb8d1ec974214ce4a581f8c528ae57 < e19201b0c67da5146eaac06fd3d44bd7945c3448affected
LinuxLinuxbee88cd5bd83d40b8aec4d6cb729378f707f6197 < 3fdd8c83e83fa5e82f1b5585245c51e0355c9f46affected
LinuxLinuxbee88cd5bd83d40b8aec4d6cb729378f707f6197 < 2d4a83a44428de45bfe9dccb0192a3711d1097e0affected
LinuxLinuxbee88cd5bd83d40b8aec4d6cb729378f707f6197 < 17bd3bd82f9f79f3feba15476c2b2c95a9b11ff8affected
LinuxLinux6.10affected
LinuxLinux0 < 6.10unaffected
LinuxLinux6.10.14 <= 6.10.*unaffected
LinuxLinux6.11.3 <= 6.11.*unaffected
LinuxLinux6.12 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References