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 CA3CE4B1265 for ; Thu, 3 Sep 2026 13:48:38 +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=1788443340; cv=none; b=mSeM+bp3NvwGZXHcndUx/+NjyJC3wv15FQebP8Xc3HzSW5fxpi7RhuARicahgCBfrwHM4G3D/Z7sQliY3+XoKUpJje8+T/sVPEv5qAFCU0r1AI4nf9n4wea4MBg6uKZLJks3K38H6igeYGycVEM3TXOc0Bi4QyzQKyZ7P6apojI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788443340; c=relaxed/simple; bh=GqqboMv0EwhG4eRG/VHntTyyJkgh8FhmoA2tyb3Vk5U=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=rrt0fczx6f2Rod0g5xfeuxxQFNeQ3Dd/FXzNY/vWicnddtepiMI380zRIqWVzXcJJ46kE399NXdeTcKQ8TMeRkfl8hzFwxBjpeISJwPKqQNj2FkXsx0eaNQ2qkRFejsnWKa0TmHuK5UPl7/Je6gzki1rYv6c1lxVG2elVUmUkuQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ii3Mus2Y; 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="ii3Mus2Y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF3CE1F00AC4; Thu, 3 Sep 2026 13:48:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788443318; bh=MeP+h4EdOqogCNTLq/fHq1GpZR3tLI6009CkNbqjeXs=; h=Subject:To:Cc:From:Date; b=ii3Mus2YdGU6LiQge9/9/3t7Wv7qlJ7nBZbeZxWnAh/8OuWkgDP+S9s6EwdmQ77Xe eKt5FPgFZHJJuoykU8p8kcPF0SaLIX8bsBwoWQg0+rFsUm6XJEpCLxW+R0K6iMB+EZ L/x/ARkbe4qumODdv5xg+3MBj18/l6xZkCLKsk1U= Subject: FAILED: patch "[PATCH] smb: client: fix UAF and buffer leak in cifs_check_trans2()" failed to apply to 6.1-stable tree To: sorenson@redhat.com,linkinjeon@kernel.org,pc@manguebit.org Cc: From: Date: Thu, 03 Sep 2026 15:26:04 +0200 Message-ID: <2026090304-drowsily-unread-e280@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 730d0bb19507b9e19c2fe5343109ac618e2fbce5 # git commit -s git send-email --to '' --in-reply-to '2026090304-drowsily-unread-e280@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 730d0bb19507b9e19c2fe5343109ac618e2fbce5 Mon Sep 17 00:00:00 2001 From: Frank Sorenson Date: Wed, 12 Aug 2026 21:39:51 -0500 Subject: [PATCH] smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2 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 diff --git a/fs/smb/client/smb1transport.c b/fs/smb/client/smb1transport.c index 66daa5a37e4a..42e95cc1bd89 100644 --- a/fs/smb/client/smb1transport.c +++ b/fs/smb/client/smb1transport.c @@ -449,10 +449,18 @@ 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(server, mid, true); + return true; + } return false; + } mid->multiRsp = true; if (mid->resp_buf) { /* merge response - fix up 1st*/