packet: use ubuf_info completion for TX_RING packets

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98503
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-18 16:17:01 UTC
Updated2026-10-19 10:19:03 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: packet: use ubuf_info completion for TX_RING packets tpacket_snd sends skbs with frags pointing into its ring slots. Slots are released when skb->destructor is called. A call to skb_orphan calls skb->destructor before the skb is freed. This can cause the slot to be reused while still linked into the skb. Switch to standard zerocopy completion (ubuf_info) so the slot is only released once all references to the payload are freed or copied. Restore skb->destructor to standard sock_wfree. The ubuf_info completion callback can be called with a NULL skb, but only from net_zcopy_put and related API, used by zerocopy implementations that hold their own reference on the uarg, such as MSG_ZEROCOPY. This uarg is only ever completed from skb_zcopy_clear, so skb is always set. To prevent userspace from aliasing in-flight state on shared ring slots, allocate tpacket_uarg per packet, rather than per slot. This adds a small allocation to the transmit path. Use standard kmalloc to allow backporting to stable kernels. The uarg holds an sk_wmem_alloc reference, rather than an sk_refcnt reference. packet_free_tx_ring waits on sk_wmem_alloc before freeing the ring pages. Always allocate vec->deferred for tx_ring so page-backed rings also wait on sk_wmem_alloc when skb_copy_ubufs drops page refs before calling tpacket_ubuf_complete. Drop the tx_ring.pg_vec test that tpacket_destruct_skb performed before accessing the slot. The sk_wmem_alloc reference now guarantees that the slot is valid. The test is also not sufficient by itself, as it reads pg_vec without pg_vec_lock, so it can race with packet_set_ring. As a result a slot is released when its payload is copied, which can be before transmission (e.g., in skb_orphan_frags_rx). If copied before skb_tx_timestamp() is called, no slot timestamp is recorded, similar to when skb_orphan() was called early in the datapath before this patch. Revert the now unused previous skb_zcopy_.._nouarg infra. Depends on commit 992cc9f94ca9 ("net/packet: defer vmalloc TX_RING free until skbs finish").

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 5cd8d46ea1562be80063f53c7c6a5f40224de623 e67c455d79fbf709a94965f09a2be6bf4f4ba5fd git Not specified
CNA Linux Linux affected 5cd8d46ea1562be80063f53c7c6a5f40224de623 eda9bcb721f15a93746a99eabda33d80b86404fd git Not specified
CNA Linux Linux affected 5cd8d46ea1562be80063f53c7c6a5f40224de623 2a0c9afefc0ecea2cc30ccfbbbc98182a0986191 git Not specified
CNA Linux Linux affected 5cd8d46ea1562be80063f53c7c6a5f40224de623 9518405613863d0bf0700927a21367f5942cf058 git Not specified
CNA Linux Linux affected 67f6fba765ef8cb19089d476e3c367212a2fbdfd git Not specified
CNA Linux Linux affected f2a67e68dbaeae7c88e5522873d7b908911f9f77 git Not specified
CNA Linux Linux affected 4.14.86 4.15 semver Not specified
CNA Linux Linux affected 4.19.7 4.20 semver Not specified
CNA Linux Linux affected 4.20 Not specified
CNA Linux Linux unaffected 4.20 semver Not specified
CNA Linux Linux unaffected 6.12.112 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.55 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.9 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/e67c455d79fbf709a94965f09a2be6bf4f4ba5fd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9518405613863d0bf0700927a21367f5942cf058 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/eda9bcb721f15a93746a99eabda33d80b86404fd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2a0c9afefc0ecea2cc30ccfbbbc98182a0986191 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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