{"id":"CVE-2026-80925","state":"PUBLISHED","title":"vlan: fix skb_under_panic and races when toggling HW VLAN offload","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nvlan: fix skb_under_panic and races when toggling HW VLAN offload\n\nToggling hardware VLAN TX offload (NETIF_F_HW_VLAN_CTAG_TX or\nNETIF_F_HW_VLAN_STAG_TX) on a lower device invokes vlan_transfer_features(),\nwhich dynamically changed vlandev->hard_header_len.\n\nThis causes two issues:\n1. Lockless TX paths (e.g. packet_snd in af_packet.c, ip6_finish_output2)\n   read dev->hard_header_len without holding RTNL lock. Mutating\n   hard_header_len dynamically under RTNL creates a data race where upper\n   layers reserve insufficient headroom based on a stale hard_header_len,\n   resulting in skb_under_panic when vlan_dev_hard_header() is called.\n2. In addition, vlan_transfer_features() updated hard_header_len without\n   updating header_ops, causing a mismatch between allocated headroom\n   and header creation.\n\nAlways setting dev->hard_header_len = real_dev->hard_header_len and\ndev->needed_headroom = real_dev->needed_headroom + VLAN_HLEN unconditionally\nensures:\n- dev->hard_header_len remains 100% static and immutable at real_dev->hard_header_len,\n  eliminating all dynamic runtime updates and data races on hard_header_len.\n- Upper layers allocating skbs via LL_RESERVED_SPACE() will always reserve\n  sufficient headroom for software VLAN tag insertion (real_dev->hard_header_len +\n  real_dev->needed_headroom + VLAN_HLEN).\n- vlandev inherits real_dev->needed_tailroom so underlying trailer/padding/ICV\n  requirements are honored.\n- AF_PACKET SOCK_RAW network header offsets remain correctly aligned at\n  real_dev->hard_header_len.\n- vlan_header_ops is used unconditionally.\n\nNote to stable teams: Make sure to backport these commits:\n\ne16e960d55a4 (\"ipvlan: inherit needed_headroom and needed_tailroom from phy_dev\")\ncef51860becd (\"macvlan: inherit needed_headroom and needed_tailroom from lowerdev\")","publishedAt":"2026-09-09T16:19:44.748Z","updatedAt":"2026-10-30T12:31:26.687Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"69f2fc6e761ee68a4c0c8e416ae88c573d4d7319","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"b38d7a4bc9c17e1d437696da25f9fbc286614d9d","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"b30fe4de285b9bdaf9508740191f69f7cd83b8fa","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"1517d1996b5236fe69eccd9d253f725e06996eb1","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"a29f3b884ba50217e6f50414f568073221e2bb07","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"447cbe95ebb95392b5d8f6a01c0556826919ce23","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/8021q/vlan_dev.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.111","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.3","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/8021q/vlan_dev.c"]}],"references":["https://git.kernel.org/stable/c/69f2fc6e761ee68a4c0c8e416ae88c573d4d7319","https://git.kernel.org/stable/c/b38d7a4bc9c17e1d437696da25f9fbc286614d9d","https://git.kernel.org/stable/c/b30fe4de285b9bdaf9508740191f69f7cd83b8fa","https://git.kernel.org/stable/c/1517d1996b5236fe69eccd9d253f725e06996eb1","https://git.kernel.org/stable/c/a29f3b884ba50217e6f50414f568073221e2bb07","https://git.kernel.org/stable/c/447cbe95ebb95392b5d8f6a01c0556826919ce23"],"weaknesses":[],"ingestedAt":"2026-10-30T12:50:04.827Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/80xxx/CVE-2026-80925.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80925","state":"PUBLISHED","datePublished":"2026-09-09T16:19:44.748Z","dateUpdated":"2026-10-30T12:31:26.687Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-26T14:34:25.802Z"},"containers":{"cna":{"title":"vlan: fix skb_under_panic and races when toggling HW VLAN offload","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nvlan: fix skb_under_panic and races when toggling HW VLAN offload\n\nToggling hardware VLAN TX offload (NETIF_F_HW_VLAN_CTAG_TX or\nNETIF_F_HW_VLAN_STAG_TX) on a lower device invokes vlan_transfer_features(),\nwhich dynamically changed vlandev->hard_header_len.\n\nThis causes two issues:\n1. Lockless TX paths (e.g. packet_snd in af_packet.c, ip6_finish_output2)\n   read dev->hard_header_len without holding RTNL lock. Mutating\n   hard_header_len dynamically under RTNL creates a data race where upper\n   layers reserve insufficient headroom based on a stale hard_header_len,\n   resulting in skb_under_panic when vlan_dev_hard_header() is called.\n2. In addition, vlan_transfer_features() updated hard_header_len without\n   updating header_ops, causing a mismatch between allocated headroom\n   and header creation.\n\nAlways setting dev->hard_header_len = real_dev->hard_header_len and\ndev->needed_headroom = real_dev->needed_headroom + VLAN_HLEN unconditionally\nensures:\n- dev->hard_header_len remains 100% static and immutable at real_dev->hard_header_len,\n  eliminating all dynamic runtime updates and data races on hard_header_len.\n- Upper layers allocating skbs via LL_RESERVED_SPACE() will always reserve\n  sufficient headroom for software VLAN tag insertion (real_dev->hard_header_len +\n  real_dev->needed_headroom + VLAN_HLEN).\n- vlandev inherits real_dev->needed_tailroom so underlying trailer/padding/ICV\n  requirements are honored.\n- AF_PACKET SOCK_RAW network header offsets remain correctly aligned at\n  real_dev->hard_header_len.\n- vlan_header_ops is used unconditionally.\n\nNote to stable teams: Make sure to backport these commits:\n\ne16e960d55a4 (\"ipvlan: inherit needed_headroom and needed_tailroom from phy_dev\")\ncef51860becd (\"macvlan: inherit needed_headroom and needed_tailroom from lowerdev\")"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"69f2fc6e761ee68a4c0c8e416ae88c573d4d7319","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"b38d7a4bc9c17e1d437696da25f9fbc286614d9d","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"b30fe4de285b9bdaf9508740191f69f7cd83b8fa","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"1517d1996b5236fe69eccd9d253f725e06996eb1","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"a29f3b884ba50217e6f50414f568073221e2bb07","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"447cbe95ebb95392b5d8f6a01c0556826919ce23","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/8021q/vlan_dev.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.111","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.3","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/8021q/vlan_dev.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/69f2fc6e761ee68a4c0c8e416ae88c573d4d7319"},{"url":"https://git.kernel.org/stable/c/b38d7a4bc9c17e1d437696da25f9fbc286614d9d"},{"url":"https://git.kernel.org/stable/c/b30fe4de285b9bdaf9508740191f69f7cd83b8fa"},{"url":"https://git.kernel.org/stable/c/1517d1996b5236fe69eccd9d253f725e06996eb1"},{"url":"https://git.kernel.org/stable/c/a29f3b884ba50217e6f50414f568073221e2bb07"},{"url":"https://git.kernel.org/stable/c/447cbe95ebb95392b5d8f6a01c0556826919ce23"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:31:26.687Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.111"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.51"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.2.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}