CVE-2026-22979

Description

In the Linux kernel, the following vulnerability has been resolved:net: fix memory leak in skb_segment_list for GRO packetsWhen skb_segment_list() is called during packet forwarding, it handlespackets that were aggregated by the GRO engine.Historically, the segmentation logic in skb_segment_list assumes thatindividual segments are split from a parent SKB and may need to carrytheir own socket memory accounting. Accordingly, the code transferstruesize from the parent to the newly created segments.Prior to commit ed4cccef64c1 (gro: fix ownership transfer), thistruesize subtraction in skb_segment_list() was valid because fragmentsstill carry a reference to the original socket.However, commit ed4cccef64c1 (gro: fix ownership transfer) changedthis behavior by ensuring that fraglist entries are explicitlyorphaned (skb->sk = null) to prevent illegal orphaning later in thestack. This change meant that the entire socket memory charge remainedwith the head SKB, but the corresponding accounting logic inskb_segment_list() was never updated.As a result, the current code unconditionally adds each fragmentstruesize to delta_truesize and subtracts it from the parent SKB. Sincethe fragments are no longer charged to the socket, this subtractionresults in an effective under-count of memory when the head is freed.This causes sk_wmem_alloc to remain non-zero, preventing socketdestruction and leading to a persistent memory leak.The leak can be observed via KMEMLEAK when tearing down the networkingenvironment:unreferenced object 0xffff8881e6eb9100 (size 2048): comm ping, pid 6720, jiffies 4295492526 backtrace: kmem_cache_alloc_noprof+0x5c6/0x800 sk_prot_alloc+0x5b/0x220 sk_alloc+0x35/0xa00 inet6_create.part.0+0x303/0x10d0 __sock_create+0x248/0x640 __sys_socket+0x11b/0x1d0Since skb_segment_list() is exclusively used for SKB_GSO_FRAGLISTpackets constructed by GRO, the truesize adjustment is removed.The call to skb_release_head_state() must be preserved. As documented incommit cf673ed0e057 (net: fix fraglist segmentation reference countleak), it is still required to correctly drop references to SKBextensions that may be overwritten during __copy_skb_header().

Risk Information

Associated Vulnerability

Patch Details

References

https://nvd.nist.gov/vuln/detail/CVE-2023-1234
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-1234