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CVE PROGRAM SOURCE RECORDUnscored

CVE-2026-80925

vlan: fix skb_under_panic and races when toggling HW VLAN offload

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: vlan: fix skb_under_panic and races when toggling HW VLAN offload Toggling hardware VLAN TX offload (NETIF_F_HW_VLAN_CTAG_TX or NETIF_F_HW_VLAN_STAG_TX) on a lower device invokes vlan_transfer_features(), which dynamically changed vlandev->hard_header_len. This causes two issues: 1. Lockless TX paths (e.g. packet_snd in af_packet.c, ip6_finish_output2) read dev->hard_header_len without holding RTNL lock. Mutating hard_header_len dynamically under RTNL creates a data race where upper layers reserve insufficient headroom based on a stale hard_header_len, resulting in skb_under_panic when vlan_dev_hard_header() is called. 2. In addition, vlan_transfer_features() updated hard_header_len without updating header_ops, causing a mismatch between allocated headroom and header creation. Always setting dev->hard_header_len = real_dev->hard_header_len and dev->needed_headroom = real_dev->needed_headroom + VLAN_HLEN unconditionally ensures: - dev->hard_header_len remains 100% static and immutable at real_dev->hard_header_len, eliminating all dynamic runtime updates and data races on hard_header_len. - Upper layers allocating skbs via LL_RESERVED_SPACE() will always reserve sufficient headroom for software VLAN tag insertion (real_dev->hard_header_len + real_dev->needed_headroom + VLAN_HLEN). - vlandev inherits real_dev->needed_tailroom so underlying trailer/padding/ICV requirements are honored. - AF_PACKET SOCK_RAW network header offsets remain correctly aligned at real_dev->hard_header_len. - vlan_header_ops is used unconditionally. Note to stable teams: Make sure to backport these commits: e16e960d55a4 ("ipvlan: inherit needed_headroom and needed_tailroom from phy_dev") cef51860becd ("macvlan: inherit needed_headroom and needed_tailroom from lowerdev")

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < b38d7a4bc9c17e1d437696da25f9fbc286614d9daffected
  • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < b30fe4de285b9bdaf9508740191f69f7cd83b8faaffected
  • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < 1517d1996b5236fe69eccd9d253f725e06996eb1affected
  • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < a29f3b884ba50217e6f50414f568073221e2bb07affected
  • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < 447cbe95ebb95392b5d8f6a01c0556826919ce23affected

Linux Linux

Default version status: affected

  • 2.6.12affected
  • 0 to < 2.6.12unaffected
  • 6.6.158 to ≤ 6.6.*unaffected
  • 6.12.111 to ≤ 6.12.*unaffected
  • 6.18.51 to ≤ 6.18.*unaffected
  • 7.2.3 to ≤ 7.2.*unaffected
  • 7.3 to ≤ *unaffected

References