{"id":"CVE-2026-98503","revision":"04870c9714d64c2fa9cd620e6eb809e4","records":[{"revision":"04870c9714d64c2fa9cd620e6eb809e4","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-98503","aliases":[],"title":"packet: use ubuf_info completion for TX_RING packets","description":"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\").","state":0,"publishedAt":"2026-10-18T15:17:03.904+00:00","modifiedAt":"2026-10-19T09:20:42.115+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"include/linux/skbuff.h\",\n \"net/packet/af_packet.c\"\n ],\n \"versions\": [\n {\n \"version\": \"5cd8d46ea1562be80063f53c7c6a5f40224de623\",\n \"lessThan\": \"e67c455d79fbf709a94965f09a2be6bf4f4ba5fd\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"5cd8d46ea1562be80063f53c7c6a5f40224de623\",\n \"lessThan\": \"eda9bcb721f15a93746a99eabda33d80b86404fd\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"5cd8d46ea1562be80063f53c7c6a5f40224de623\",\n \"lessThan\": \"2a0c9afefc0ecea2cc30ccfbbbc98182a0986191\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"5cd8d46ea1562be80063f53c7c6a5f40224de623\",\n \"lessThan\": \"9518405613863d0bf0700927a21367f5942cf058\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"67f6fba765ef8cb19089d476e3c367212a2fbdfd\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"f2a67e68dbaeae7c88e5522873d7b908911f9f77\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"4.14.86\",\n \"lessThan\": \"4.15\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"4.19.7\",\n \"lessThan\": \"4.20\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"include/linux/skbuff.h\",\n \"net/packet/af_packet.c\"\n ],\n \"versions\": [\n {\n \"version\": \"4.20\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"4.20\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.112\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.55\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2.9\",\n \"lessThanOrEqual\": \"7.2.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.3\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/e67c455d79fbf709a94965f09a2be6bf4f4ba5fd","https://git.kernel.org/stable/c/eda9bcb721f15a93746a99eabda33d80b86404fd","https://git.kernel.org/stable/c/2a0c9afefc0ecea2cc30ccfbbbc98182a0986191","https://git.kernel.org/stable/c/9518405613863d0bf0700927a21367f5942cf058"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98503","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98503","identifiers":["CVE-2026-98503"]},"retained":false,"historicalAffected":[]}],"coverage":[]}