From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5A62257F72F for ; Wed, 9 Sep 2026 16:20:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788970807; cv=none; b=dnIrnfJ/28voFVP9tbVX3HrSKDANWwV5T1OZMzH2k+yYrYye3gDthincehmt6ma+nOitnLjaKf3RMhC0ErGQw0qcj7fMTCaqweLq65uCB26RA0f4AkhDp1LIadKIjFCknZ5Q4Yh5Fo4LbXN3kDMiuHxEEyHHImIyrxdU7HsDoBk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788970807; c=relaxed/simple; bh=aeFI/92AoYbgM7C34kIC51ZxEEYrv300ewnIv0oc0pk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=osb9+hWAveJhpqVkWmBa2psRrkvJBd0OOsGGCikN/iqZC1iLW4dY5MRjoqe67/0OtWRKXjCXo6rmINp5kN9IlZ5qSkC3MJirmA2g0phXLbKvnp4DtmprzdpePbxxBDH8roPj3II0Q45tH3+jUo7YXfnUfbLWTzFdYSDiCiXSTCM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=tPEbyxG/; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="tPEbyxG/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5B1EE1F000FF; Wed, 9 Sep 2026 16:20:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788970805; bh=iy9hmhQnB2Iem9EWn7mqMSG/CpVbS2pTqGLPz8npXIc=; h=From:To:Cc:Subject:Date:Reply-To; b=tPEbyxG/GwodFr/VEquG8qtUSuKwBwHtLxQxrX2mAejO6PkEDfE6x/Z2X/BRn6Yjt Z2zT5Mi0whQy9Y9yimZKBtjyONEYqSbvbltkC8NenKrcojZQ2THLWPSYDHJsaCZUQc gpJt8J4XS+2t+Ow/BZz98nEivewIl/QeWC8dW8b4= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-80925: vlan: fix skb_under_panic and races when toggling HW VLAN offload Date: Wed, 9 Sep 2026 18:19:47 +0200 Message-ID: <2026090943-CVE-2026-80925-d4f2@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3543; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=H7kvpUbNGXJojhuMALDHmsP98NjpghCoi63G12L+oyQ=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkL2+VjTV7YrKy1mN1c86C3S1m48b8s+3YBlUXtYVyrP qtWChl1xLIwCDIxyIopsnzZxnN0f8UhRS9D29Mwc1iZQIYwcHEKwERWHGaYXzNz2sITf5u0fL4H MHp0lvmtvrZFnWF+5bcPKscUPLek2fE9vrFjq0J7GFM5AA== X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman 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") The Linux kernel CVE team has assigned CVE-2026-80925 to this issue. Affected and fixed versions =========================== Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.2.3 with commit a29f3b884ba50217e6f50414f568073221e2bb07 Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.3-rc1 with commit 447cbe95ebb95392b5d8f6a01c0556826919ce23 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-80925 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: net/8021q/vlan_dev.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/a29f3b884ba50217e6f50414f568073221e2bb07 https://git.kernel.org/stable/c/447cbe95ebb95392b5d8f6a01c0556826919ce23