All of lore.kernel.org
 help / color / mirror / Atom feed
* FAILED: patch "[PATCH] smb: client: fix UAF and buffer leak in cifs_check_trans2()" failed to apply to 6.1-stable tree
@ 2026-09-03 13:26 gregkh
  2026-09-07 22:45 ` [PATCH 6.1.y 1/4] cifs: Remove the server pointer from smb_message Sasha Levin
  0 siblings, 1 reply; 5+ messages in thread
From: gregkh @ 2026-09-03 13:26 UTC (permalink / raw)
  To: sorenson, linkinjeon, pc; +Cc: stable


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 <stable@vger.kernel.org>.

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
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --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 <sorenson@redhat.com>
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 <sorenson@redhat.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>

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*/


^ permalink raw reply related	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2026-09-07 22:46 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-09-03 13:26 FAILED: patch "[PATCH] smb: client: fix UAF and buffer leak in cifs_check_trans2()" failed to apply to 6.1-stable tree gregkh
2026-09-07 22:45 ` [PATCH 6.1.y 1/4] cifs: Remove the server pointer from smb_message Sasha Levin
2026-09-07 22:45   ` [PATCH 6.1.y 2/4] cifs: Scripted clean up fs/smb/client/fscache.h Sasha Levin
2026-09-07 22:45   ` [PATCH 6.1.y 3/4] cifs: SMB1 split: Create smb1proto.h for SMB1 declarations Sasha Levin
2026-09-07 22:45   ` [PATCH 6.1.y 4/4] smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2 Sasha Levin

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.