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 D51A4223DD4 for ; Sat, 15 Aug 2026 06:35:52 +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=1786775754; cv=none; b=MhqVkFPWzOmz8YuAqI5hXrl5NbETms0WnuLn0HBcv+p4uhXhAUFjOJ3u91L9qC0z0mbqezSbwURGLfVngsmdn7qL/ojS2JiaM/C8a5akg3G/uabek7A4VGs3GfoEfWoktdjamhwaxcwmJNSmMg5lGhF4SALRcYkOaCK79C/eVlY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786775754; c=relaxed/simple; bh=cJ2/Di15XGawkthu0j9qNp/bz38Lrd5Ktu3eL5/km5o=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=sZ2Xub6r18snp2VkNLnW7F3RrH5wEQPco5VbAwV8UimIcbNnpME7XDBLkiaZodtAXaTS/RJdP90KTDxjj+upW5fKSJuK4qgTl5aDdU33Dp4holGaZLdVY4Ktxj0lM4uzLyczok4s+8Vt2RVM05GOEyxVeGi6DbsotDw+lDUE+XQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=y75rMbtZ; 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="y75rMbtZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 349371F000E9; Sat, 15 Aug 2026 06:35:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786775752; bh=0psXxDf0Qx7TSQF3aqKLkMUyp75kPiTmOpbOmMgekPg=; h=From:To:Cc:Subject:Date:Reply-To; b=y75rMbtZWDgCXhBqfN38ooXvKi4dNNi5waEL35XkRNZMFIO+1SxNPIWJhhg3jn+UG rtS33pqOaBVrpoobfOQFhSTEsGUvPICTXMy9fCpVkxFJtV1aaJBHqEXT/30b9aW2bf hpRUvrqza86nwebKgzNQm+FKEu6Rf1dzK+gj5aPE= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-74343: kernfs: fix xattr race condition with multiple superblocks Date: Sat, 15 Aug 2026 15:11:10 +0900 Message-ID: <2026081558-CVE-2026-74343-c22d@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=3146; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=Whe6OlQFTIcj9MXm8JHHRRf8kLc6knSVRxD20apJLfA=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkNjELqnTxem7Ujt5Rk7d70Y4Hz9ZsGt8PX1Na5yy+9d mnRfFPzjlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZjIzoMM89QWxG3hLuW6eVuD k++SY63jnv4VjAzzSxu7T9ffXJnb/bHjvHuVWeSyjKUsAA== 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: kernfs: fix xattr race condition with multiple superblocks Multiple superblocks with different namespaces can share the same kernfs_node when kernfs_test_super() finds a matching root but different namespace. This means multiple inodes from different superblocks can reference the same kernfs_node->iattr->xattrs structure. The VFS layer only holds per-inode locks during xattr operations, which is insufficient to serialize concurrent xattr modifications on the shared kernfs_node. This can lead to race conditions in simple_xattr_set() where the lookup->replace/remove sequence is not atomic with respect to operations from other superblocks. Fix this by protecting xattr operations with the existing hashed kernfs_locks->open_file_mutex[] array, which is already used to protect per-node open file data. The hashed mutex array provides scalable per-node serialization (scaled by CPU count, up to 1024 locks on 32+ CPU systems) with zero memory overhead. Changes: - Rename open_file_mutex[] to node_mutex[] to reflect dual purpose - Add kernfs_node_lock_ptr() and kernfs_node_lock() helpers - Protect simple_xattr_set() calls in kernfs_xattr_set() and kernfs_vfs_user_xattr_set() with the hashed mutex - Update file.c to use new helpers via compatibility wrappers - Update documentation to explain the extended lock usage The Linux kernel CVE team has assigned CVE-2026-74343 to this issue. Affected and fixed versions =========================== Issue introduced in 7.1 with commit b32c4a213698ab351b44da2fd1b2a5976c7fa033 and fixed in 7.1.5 with commit bf53db51359939755084d08156684ed649489592 Issue introduced in 7.1 with commit b32c4a213698ab351b44da2fd1b2a5976c7fa033 and fixed in 7.2-rc1 with commit 6a07814ff643b5c8e1353d8c6229f52fde205cde 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-2026-74343 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: fs/kernfs/file.c fs/kernfs/inode.c fs/kernfs/kernfs-internal.h fs/kernfs/mount.c include/linux/kernfs.h 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/bf53db51359939755084d08156684ed649489592 https://git.kernel.org/stable/c/6a07814ff643b5c8e1353d8c6229f52fde205cde