{"schema":"threatline.record/2","record":{"id":"CVE-2026-98271","aliases":[],"summary":"net: skbuff: do not leave stale header offsets after pskb_carve()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: skbuff: do not leave stale header offsets after pskb_carve()\n\npskb_carve_inside_header() and pskb_carve_inside_nonlinear() remove\nthe first bytes of a packet and reallocate skb->head.\n\nAll the headers that were present before the operation are gone,\nbut both functions call skb_headers_offset_update(skb, 0), which\nis a no-op : skb->mac_header, skb->network_header,\nskb->transport_header and skb->csum_start keep their old values and\nnow describe bytes which are no longer there.\n\nBoth helpers size the new head from the old skb_end_offset(), so the\nstale offsets still land inside the new allocation. They point past\nskb_tail_pointer() though, to bytes that were never initialized.\n\npskb_carve_inside_nonlinear() is the worst case, because it leaves a\nzombie skb with an empty linear part (skb->data ==\nskb_tail_pointer(skb), skb_headlen(skb) == 0), while\nskb_mac_header_was_set() is still true and skb->mac_header is way\nahead of skb->data.\n\nThe only user of pskb_extract() is rds_tcp_data_recv(), and the\ncarved skb is queued on tinc->ti_skb_list. When the RDS incoming\nmessage is released, rds_tcp_inc_free() calls skb_queue_purge(),\nwhich frees the skbs with SKB_DROP_REASON_QUEUE_PURGE. This is\nvisible from drop_monitor, which then tries to pull back to the\n(bogus) mac header :\n\nskbuff: __skb_pull(len=234)\nskb len=6968 data_len=6968 headroom=0 headlen=0 tailroom=0\nend-tail=384 mac=(234,14) mac_len=14 net=(248,40) trans=288\nshinfo(txflags=0 nr_frags=1 gso(size=1428 type=16 segs=5))\ncsum(0x100120 start=288 offset=16 ip_summed=3 complete_sw=0 valid=1 level=0)\nhash(0x7b446c6c sw=0 l4=1) proto=0x86dd pkttype=0 iif=60\nkernel BUG at ./include/linux/skbuff.h:2847!\n\nAdd skb_carve_reset_headers() to mark the mac and transport headers\nas not set, reset the network header, clear skb->mac_len, and drop\na now meaningless CHECKSUM_PARTIAL (csum_start no longer describes\nanything).\n\nInvalidate the inner offsets as well. Unlike mac_header and\ntransport_header they have no \"unset\" sentinel, so a leftover\nnon-zero value still looks like a real header. Zero\nskb->inner_mac_header, skb->inner_network_header,\nskb->inner_transport_header, skb->inner_protocol and\nskb->encapsulation, so that all the header state is invalidated in\none place.\n\nv2: fixed an inaccurate changelog. The stale offsets stay inside the\n    new skb->head, which is never smaller than the old one, they\n    simply point past skb_tail_pointer() to bytes that are gone.\n    Thanks to Xuanqiang Luo for insisting on this.\n    Also invalidate the inner header state, as suggested by the\n    netdev AI review :\n    https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260911114922.621937-1-edumazet%40google.com","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98271","source_modified_at":"2026-10-19T09:16:41.976Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"6fa01ccd883021105e9f8af7d04b9f156fa3494a","lessThan":"75e4a3e62531738c124c8555a626426fca29d392","status":"affected","versionType":"git"},{"version":"6fa01ccd883021105e9f8af7d04b9f156fa3494a","lessThan":"bff8a8e53a6d290bc2777bde36d3cb6317b8463d","status":"affected","versionType":"git"},{"version":"6fa01ccd883021105e9f8af7d04b9f156fa3494a","lessThan":"12929ed66a5166177ef5f06d3da81e4f99993e90","status":"affected","versionType":"git"},{"version":"6fa01ccd883021105e9f8af7d04b9f156fa3494a","lessThan":"a5117e1eccac6ee3bd4aed7cacf8ebcb6b3eb309","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98271","source_modified_at":"2026-10-19T09:16:41.976Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"4.7","status":"affected"},{"version":"0","lessThan":"4.7","status":"unaffected","versionType":"semver"},{"version":"6.12.112","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.54","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.8","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-2026-98271","source_modified_at":"2026-10-19T09:16:41.976Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"75e4a3e62531738c124c8555a626426fca29d392","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98271","source_modified_at":"2026-10-19T09:16:41.976Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"12929ed66a5166177ef5f06d3da81e4f99993e90","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":0.00175,"percentile":0.06669,"score_date":"2026-10-23"},"published_at":"2026-10-06T08:45:33.298Z","modified_at":"2026-10-19T09:16:41.976Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-98271","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-19T09:16:41.976Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-98271","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/75e4a3e62531738c124c8555a626426fca29d392"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/bff8a8e53a6d290bc2777bde36d3cb6317b8463d"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/12929ed66a5166177ef5f06d3da81e4f99993e90"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/a5117e1eccac6ee3bd4aed7cacf8ebcb6b3eb309"}],"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":"2026-10-19T09:16:41.976Z","content_hash":"a43ee8532bd46bf2dcb035cb70e2e3fe52b60937341c6d994f499c03a0dfc16a"}}