CVE-2026-53365 — vsock/virtio: fix zerocopy completion for multi-skb sends

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: vsock/virtio: fix zerocopy completion for multi-skb sends When a large message is fragmented into multiple skbs, the zerocopy uarg is only allocated and attached to the last skb in the loop. Non-final skbs carry pinned user pages with no completion tracking, so the kernel has no way to notify userspace when those pages are safe to reuse. If the loop breaks early the uarg is never allocated at all, leaking pinned pages with no completion notification. Fix this by following the approach used by TCP: allocate the zerocopy uarg (if not provided by the caller) before the send loop and attach it to every skb via skb_zcopy_set(), which takes a reference per skb. Each skb's completion properly decrements the refcount, and the notification only fires after the last skb is freed. On failure, if no data was sent, the uarg is cleanly aborted via net_zcopy_put_abort(). This issue was initially discovered by sashiko while reviewing commit 1cb36e252211 ("vsock/virtio: fix MSG_ZEROCOPY pinned-pages accounting") but was pre-existing.

Affected (CNA)

Vendor / product	Versions
Linux / Linux	affected 581512a6dc939ef122e49336626ae159f3b8a345 before 293fe8f2d1b5ac464ca16a8eba09571bbbb34ba9; affected 581512a6dc939ef122e49336626ae159f3b8a345 before 76b995bc57bd90cb6e954e1966fbd8786da47f0d; affected 581512a6dc939ef122e49336626ae159f3b8a345 before b3155f2b78db21e99256bcf7eb902f24ff6d5338; affected 581512a6dc939ef122e49336626ae159f3b8a345 before ae38d9179190a956e2a87a69ef1dd6f451b51c4d
Linux / Linux	affected 6.7; unaffected 0 before 6.7; unaffected 6.12.97 through 6.12.; unaffected 6.18.34 through 6.18.; unaffected 7.0.11 through 7.0.; unaffected 7.1 through

CWE

No CWE identifiers supplied.

References

ADP enrichment

CISA-ADP

No English description supplied.

https://github.com/MaherAzzouzi/vsockdrop