{"schema":"threatline.record/2","record":{"id":"CVE-2026-98503","aliases":[],"summary":"packet: use ubuf_info completion for TX_RING packets","details":"In the Linux kernel, the following vulnerability has been resolved:\n\npacket: use ubuf_info completion for TX_RING packets\n\ntpacket_snd sends skbs with frags pointing into its ring slots. Slots\nare released when skb->destructor is called.\n\nA call to skb_orphan calls skb->destructor before the skb is freed.\nThis can cause the slot to be reused while still linked into the skb.\n\nSwitch to standard zerocopy completion (ubuf_info) so the slot is only\nreleased once all references to the payload are freed or copied.\nRestore skb->destructor to standard sock_wfree.\n\nThe ubuf_info completion callback can be called with a NULL skb, but\nonly from net_zcopy_put and related API, used by zerocopy implementations\nthat hold their own reference on the uarg, such as MSG_ZEROCOPY. This\nuarg is only ever completed from skb_zcopy_clear, so skb is always set.\n\nTo prevent userspace from aliasing in-flight state on shared ring\nslots, allocate tpacket_uarg per packet, rather than per slot. This\nadds a small allocation to the transmit path. Use standard kmalloc to\nallow backporting to stable kernels.\n\nThe uarg holds an sk_wmem_alloc reference, rather than an sk_refcnt\nreference. packet_free_tx_ring waits on sk_wmem_alloc before freeing\nthe ring pages. Always allocate vec->deferred for tx_ring so page-backed\nrings also wait on sk_wmem_alloc when skb_copy_ubufs drops page refs\nbefore calling tpacket_ubuf_complete.\n\nDrop the tx_ring.pg_vec test that tpacket_destruct_skb performed before\naccessing the slot. The sk_wmem_alloc reference now guarantees that the\nslot is valid. The test is also not sufficient by itself, as it reads\npg_vec without pg_vec_lock, so it can race with packet_set_ring.\n\nAs a result a slot is released when its payload is copied, which can\nbe before transmission (e.g., in skb_orphan_frags_rx). If copied\nbefore skb_tx_timestamp() is called, no slot timestamp is recorded,\nsimilar to when skb_orphan() was called early in the datapath before\nthis patch.\n\nRevert the now unused previous skb_zcopy_.._nouarg infra.\n\nDepends on commit 992cc9f94ca9 (\"net/packet: defer vmalloc TX_RING\nfree until skbs finish\").","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98503","source_modified_at":"2026-10-19T09:20:42.115Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"5cd8d46ea1562be80063f53c7c6a5f40224de623","lessThan":"e67c455d79fbf709a94965f09a2be6bf4f4ba5fd","status":"affected","versionType":"git"},{"version":"5cd8d46ea1562be80063f53c7c6a5f40224de623","lessThan":"eda9bcb721f15a93746a99eabda33d80b86404fd","status":"affected","versionType":"git"},{"version":"5cd8d46ea1562be80063f53c7c6a5f40224de623","lessThan":"2a0c9afefc0ecea2cc30ccfbbbc98182a0986191","status":"affected","versionType":"git"},{"version":"5cd8d46ea1562be80063f53c7c6a5f40224de623","lessThan":"9518405613863d0bf0700927a21367f5942cf058","status":"affected","versionType":"git"},{"version":"67f6fba765ef8cb19089d476e3c367212a2fbdfd","status":"affected","versionType":"git"},{"version":"f2a67e68dbaeae7c88e5522873d7b908911f9f77","status":"affected","versionType":"git"},{"version":"4.14.86","lessThan":"4.15","status":"affected","versionType":"semver"},{"version":"4.19.7","lessThan":"4.20","status":"affected","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98503","source_modified_at":"2026-10-19T09:20:42.115Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"4.20","status":"affected"},{"version":"0","lessThan":"4.20","status":"unaffected","versionType":"semver"},{"version":"6.12.112","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.55","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.9","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98503","source_modified_at":"2026-10-19T09:20:42.115Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"2a0c9afefc0ecea2cc30ccfbbbc98182a0986191","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98503","source_modified_at":"2026-10-19T09:20:42.115Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"9518405613863d0bf0700927a21367f5942cf058","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98503","source_modified_at":"2026-10-19T09:20:42.115Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"4.15","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98503","source_modified_at":"2026-10-19T09:20:42.115Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"4.20","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":0.002,"percentile":0.09339,"score_date":"2026-10-23"},"published_at":"2026-10-18T15:17:03.904Z","modified_at":"2026-10-19T09:20:42.115Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-98503","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-19T09:20:42.115Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-98503","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/e67c455d79fbf709a94965f09a2be6bf4f4ba5fd"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/eda9bcb721f15a93746a99eabda33d80b86404fd"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/2a0c9afefc0ecea2cc30ccfbbbc98182a0986191"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/9518405613863d0bf0700927a21367f5942cf058"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-19T09:20:42.115Z","content_hash":"6be46152d26c3580a70abd8f60a5d0272581b687c4f85959eb9923ea9146aafb"}}