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 450493B3C18; Wed, 30 Sep 2026 19:15:45 +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=1790795746; cv=none; b=AzM6OvvvCTWtHv4RWy4U1roZx24azwGBeyw7JJFBx7SP9lkqcCtvklWr/L0CcKTPqt268/EK6oIBPjWdVLPNYFkjUSq8SC7+Fg3oDk4b7t39pFuhqiAKpGS+0+VVaLTPOVyCtRXsQTpFjl1YhiAjsRV5gpvpIu5dnlPpylEJNg8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790795746; c=relaxed/simple; bh=pMslFWzJZPm8sWwY1lHCa2fm3By0HeyrQiQAS0D4Eaw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=P4SI0MjuYH5zZTZKF/j9Hq4OZ3dHN2DTu1h/qIYXljCjc0BxpYRlPEuvgErj1j6BE6VIhPsv8hYwZk7BxXK43WwwjPYl0mq0XymU3qlLE8KwdvUKSaO+dJQ61sdx0G3Dmay295scn3ptFmw8oaiPu/IKUditMKC2zQREdkASEcU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=anIODiKP; 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="anIODiKP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A01F71F000FF; Wed, 30 Sep 2026 19:15:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790795745; bh=9rTXqsQfSfNIsnPwpdBl1feg+HdOjsvXQsZVE3I3Zk4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=anIODiKP+3yL0K9ex3n7IzCUmPe+OKIUi4g2qIuAXhOJuleBoE7tYTgKY+difQNar 5m4eyoR14tWINopfNT/DJXzEIwFL7ggyqWYx78vmyQlwvb7xz2n7PEAVbjUTG6gVPo Fz8tcski3ApMkRTsuqdGhnDFdSRosVQoMifb2F70= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Bjoern Doebel , Namjae Jeon , Paulo Alcantara Subject: [PATCH 6.6 0670/1193] smb: client: fix heap overflow in DACL owner/group rewrite Date: Wed, 30 Sep 2026 17:22:34 +0200 Message-ID: <20260930152449.129485061@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152434.301151190@linuxfoundation.org> References: <20260930152434.301151190@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bjoern Doebel commit 0ee150794c75bcd0be0e24ff3394f433cbae18cc upstream. When id_mode_to_cifs_acl rewrites an existing DACL, it allocates a buffer sized according to the on-disk DACL length reported by dacl_ptr->size. However, replace_sids_and_copy_aces may rewrite each ACE with a new owner/group SID obtained from the cifs.idmap upcall. Those SIDs can have up to SID_MAX_SUB_AUTHORITIES (15) sub-authorities, making each ACE up to 76 bytes (sizeof(struct smb_ace)). If the original DACL contains short SIDs (e.g., 1 sub-authority) while the replacement SIDs are long, the rewritten ACEs overflow the allocation. Fix this by always budgeting for worst-case SID expansion: allocate sizeof(struct smb_acl) plus num_aces * sizeof(struct smb_ace), which covers the smb_acl header and room for every ACE at maximum SID size. This replaces the previous split logic that used dacl_ptr->size for cifsacl mounts but num_aces * sizeof(struct smb_ace) for mode_from_sid mounts: both paths can trigger the same rewrite and need the same headroom. KASAN reports this as: BUG: KASAN: slab-out-of-bounds in build_sec_desc+0x1e8a/0x2680 [cifs] Write of size 4 at addr ffff8881a5e25374 by task chown/5298 ... The buggy address is located 0 bytes to the right of allocated 884-byte region [ffff8881a5e25000, ffff8881a5e25374) Cc: stable@vger.kernel.org Fixes: bc3e9dd9d104 ("cifs: Change SIDs in ACEs while transferring file ownership.") Assisted-by: Kiro:claude-opus-4.6 Signed-off-by: Bjoern Doebel Reviewed-by: Namjae Jeon Fixes: 5c3564852c58 ("cifs: Minimize the number of cifs_acl memory allocations") Signed-off-by: Paulo Alcantara Signed-off-by: Greg Kroah-Hartman --- fs/smb/client/cifsacl.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) --- a/fs/smb/client/cifsacl.c +++ b/fs/smb/client/cifsacl.c @@ -1769,11 +1769,13 @@ id_mode_to_cifs_acl(struct inode *inode, cifs_put_tlink(tlink); return rc; } - if (mode_from_sid) - nsecdesclen += - le16_to_cpu(dacl_ptr->num_aces) * sizeof(struct smb_ace); - else /* cifsacl */ - nsecdesclen += le16_to_cpu(dacl_ptr->size); + /* + * Worst case: every ACE is rewritten with a new SID of + * SID_MAX_SUB_AUTHORITIES sub-auths -> sizeof(smb_ace) each, + * plus the smb_acl header replace_sids_and_copy_aces() emits. + */ + nsecdesclen += sizeof(struct smb_acl) + + le16_to_cpu(dacl_ptr->num_aces) * sizeof(struct smb_ace); } }