Subject: FAILED: patch "[PATCH] smb: client: fix server->total_read for compound encrypted" failed to apply to 5.15-stable tree
To: sorenson@redhat.com,dhowells@redhat.com,pc@manguebit.org
Cc: <stable@vger.kernel.org>
From: <gregkh@linuxfoundation.org>
Date: Tue, 22 Sep 2026 17:08:13 +0200
Message-ID: <2026092213-aflutter-survive-4ebf@gregkh>
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The patch below does not apply to the 5.15-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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x f73726b83e4756fdaa099e1bc1143293bd57ad79
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026092213-aflutter-survive-4ebf@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:


thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f73726b83e4756fdaa099e1bc1143293bd57ad79 Mon Sep 17 00:00:00 2001
From: Frank Sorenson <sorenson@redhat.com>
Date: Wed, 16 Sep 2026 16:33:54 -0500
Subject: [PATCH] smb: client: fix server->total_read for compound encrypted
 PDUs

In receive_encrypted_standard(), server->total_read is left at the
full decrypted frame size when walking sub-PDUs of a compound encrypted
frame. As a result, cifs_handle_standard() passes this full size
to smb2_check_message(), causing the PDU length guards to incorrectly
validate the entire compound frame instead of the current sub-PDU.

This allows truncated non-last sub-PDUs to bypass length validation,
leading to out-of-bounds reads in smb2_get_data_area_len().

Fix this by setting server->total_read to the true length of the
current sub-PDU: next_cmd for non-last sub-PDUs, and the remaining
pdu_length for the last one.

Fixes: b24df3e30cbf ("cifs: update receive_encrypted_standard to handle compounded responses")
Cc: stable@vger.kernel.org
Signed-off-by: Frank Sorenson <sorenson@redhat.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>

diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index fcf7033889c7..7f2177f6fc01 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -5371,6 +5371,7 @@ receive_encrypted_standard(struct TCP_Server_Info *server,
 one_more:
 	shdr = (struct smb2_hdr *)buf;
 	next_cmd = le32_to_cpu(shdr->NextCommand);
+	server->total_read = next_cmd ? next_cmd : pdu_length;
 
 	if (*num_mids >= MAX_COMPOUND) {
 		cifs_server_dbg(VFS, "too many PDUs in compound\n");