FAILED: patch "[PATCH] ksmbd: reserve space for the UTF-16 terminator in stream info" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

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 a025c4991a7d83edc4dd339e3ea86d8ff6226eca
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026110318-lanky-disallow-4cf3@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

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

From a025c4991a7d83edc4dd339e3ea86d8ff6226eca Mon Sep 17 00:00:00 2001
From: Abdifatah Suruur <suruurism@gmail.com>
Date: Sat, 17 Oct 2026 13:54:54 +0300
Subject: [PATCH] ksmbd: reserve space for the UTF-16 terminator in stream info

smb_strtoUTF16() always writes a terminating zero UTF-16 unit after the
converted characters, but get_file_stream_info() budgets only
sizeof(struct smb2_file_stream_info) + streamlen * 2 for a stream entry
and sizeof(struct smb2_file_stream_info) + 7 * 2 for the trailing
"::$DATA" entry. When an entry exactly fills the 448-byte small response
buffer, the terminator is written two bytes past the allocation.

Reserve one extra UTF-16 unit in both budget checks. The terminator is
not part of the wire format, so the reported lengths are unchanged.

Cc: stable@vger.kernel.org
Signed-off-by: Abdifatah Suruur <suruurism@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 7efd60c36431..a1b9368504f9 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -7274,7 +7274,8 @@ static int get_file_stream_info(struct ksmbd_work *work,
 				     ":%s", &stream_name[XATTR_NAME_STREAM_LEN]);
 
 		next = sizeof(struct smb2_file_stream_info) + streamlen * 2;
-		if (next > buf_free_len) {
+		/* smbConvertToUTF16() also writes a terminating UTF-16 unit. */
+		if (next + sizeof(__le16) > buf_free_len) {
 			kfree(stream_buf);
 			break;
 		}
@@ -7299,7 +7300,7 @@ static int get_file_stream_info(struct ksmbd_work *work,
 
 out:
 	if (!S_ISDIR(stat.mode) &&
-	    buf_free_len >= sizeof(struct smb2_file_stream_info) + 7 * 2) {
+	    buf_free_len >= sizeof(struct smb2_file_stream_info) + (7 + 1) * 2) {
 		file_info = (struct smb2_file_stream_info *)
 			&rsp->Buffer[nbytes];
 		streamlen = smbConvertToUTF16((__le16 *)file_info->StreamName,