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 BDDE958E2CE; Wed, 9 Sep 2026 14:39:57 +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=1788964798; cv=none; b=FIOsJBPZ0MNOEjJCXkTnhN6Blqx4FitWEfjWSymbSPy7maVuJBkgMjYtxFcoZZkMr6GYcMG5gaea7SRYXX34gFNDOX6QcgP2F3Yoh7zNqMoLuMh4X09SuAWR6MzshLRKeP5bXuAGdF3TrV+Kwg5NO1wC7iN9LO0hi4xM/1+J4/k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788964798; c=relaxed/simple; bh=wnCK6ZBejtEuvAoraAJYZHMHEJpnf5eY1Gg4RUCsLW8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cEzgSp2MHZvLHtum+TrOUOIwUyiLHfwhd2HqUh04L+U9PCB2ZWGe6XHTLHdp46vFXbpJVEPuzaFq+4A5QoLiawuMo4VlrMwAOuyci4rTtet5ZzbBG+59GMq8TFl2jh/Le+o4cCP7ZsZkNdZWo0u9Hqw+AFZxsvX3d7I5z/t+0Us= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Gq7AV4mr; 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="Gq7AV4mr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 22AEA1F00A3A; Wed, 9 Sep 2026 14:39:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788964797; bh=OBlzEaMpfKuUXHwXX97+Bein7SSZEZdgpdn9Ohm8wdY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Gq7AV4mrWxGc+flSAxYAMZmN8C5IP0mCoB5bihWFXtOrz+TGBVQGX1tHp1JQtCXHY baOXhoBgNfms8mE0Yq9ARu0o1aJD45sFDHQP3yzA79KRP74nKLy8d6TZgjp6qEjnqz 5ddpcua1pVrQMJnwAuF9nuLs557zk2tzwvbhDkBM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Frank Sorenson , Namjae Jeon , Paulo Alcantara , Sasha Levin Subject: [PATCH 6.18 546/583] smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2 Date: Wed, 9 Sep 2026 15:43:51 +0200 Message-ID: <20260909134256.653337511@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260909134237.773280130@linuxfoundation.org> References: <20260909134237.773280130@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Frank Sorenson [ Upstream commit 730d0bb19507b9e19c2fe5343109ac618e2fbce5 ] When a valid primary TRANSACT2 response has been received (mid->resp_buf set, mid->multiRsp true) and a subsequent secondary response causes cifs_check_trans2() to return false -- either because the SMB header is invalid (malformed != 0) or because check2ndT2() rejects the PDU -- handle_mid() overwrites mid->resp_buf with the new buffer (leaking the primary buffer) and, because mid->multiRsp is set, skips the server->smallbuf/bigbuf NULL-out. When the user thread frees mid->resp_buf, server->smallbuf or server->bigbuf is left dangling; the demux thread reuses it for the next packet, resulting in a use-after-free. Combine both early-exit conditions and, when mid->multiRsp is already set, abort the pending transaction inline: set multiEnd, call dequeue_mid() with malformed=true, and return true so handle_mid() exits without touching mid->resp_buf or the server buffer pointers. Fixes: 316cf94a910f ("CIFS: Move trans2 processing to ops struct") Cc: stable@vger.kernel.org # cifs_check_trans2() is in smb1ops.c on kernels < 7.0 Signed-off-by: Frank Sorenson Signed-off-by: Namjae Jeon Signed-off-by: Paulo Alcantara [ changed dequeue_mid(server, mid, true) to the older dequeue_mid(mid, true) API ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/smb/client/smb1transport.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) --- a/fs/smb/client/smb1transport.c +++ b/fs/smb/client/smb1transport.c @@ -708,10 +708,18 @@ bool cifs_check_trans2(struct mid_q_entry *mid, struct TCP_Server_Info *server, char *buf, int malformed) { - if (malformed) - return false; - if (check2ndT2(buf) <= 0) + if (malformed || check2ndT2(buf) <= 0) { + /* mid->multiRsp blocks the server buf detach in handle_mid(); + * returning false here would leak resp_buf and leave a dangling + * server->smallbuf/bigbuf after the user thread frees resp_buf. + */ + if (mid->multiRsp) { + mid->multiEnd = true; + dequeue_mid(mid, true); + return true; + } return false; + } mid->multiRsp = true; if (mid->resp_buf) { /* merge response - fix up 1st*/