FAILED: patch "[PATCH] ksmbd: don't allow O_TRUNC open on read-only share" 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 d592a9158a112d419f341f035d18d02f8d232def
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024011805-atlantic-diffuser-53a5@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

d592a9158a11 ("ksmbd: don't allow O_TRUNC open on read-only share")
38c8a9a52082 ("smb: move client and server files to common directory fs/smb")
abdb1742a312 ("cifs: get rid of mount options string parsing")
9fd29a5bae6e ("cifs: use fs_context for automounts")
5dd8ce24667a ("cifs: missing directory in MAINTAINERS file")
332019e23a51 ("Merge tag '5.20-rc-smb3-client-fixes-part2' of git://git.samba.org/sfrench/cifs-2.6")

thanks,

greg k-h

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

From d592a9158a112d419f341f035d18d02f8d232def Mon Sep 17 00:00:00 2001
From: Namjae Jeon <linkinjeon@kernel.org>
Date: Sun, 7 Jan 2024 21:24:07 +0900
Subject: [PATCH] ksmbd: don't allow O_TRUNC open on read-only share

When file is changed using notepad on read-only share(read_only = yes in
ksmbd.conf), There is a problem where existing data is truncated.
notepad in windows try to O_TRUNC open(FILE_OVERWRITE_IF) and all data
in file is truncated. This patch don't allow  O_TRUNC open on read-only
share and add KSMBD_TREE_CONN_FLAG_WRITABLE check in smb2_set_info().

Cc: stable@vger.kernel.org
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index a2f729675183..2a335bfe25a4 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -2972,7 +2972,7 @@ int smb2_open(struct ksmbd_work *work)
 					    &may_flags);
 
 	if (!test_tree_conn_flag(tcon, KSMBD_TREE_CONN_FLAG_WRITABLE)) {
-		if (open_flags & O_CREAT) {
+		if (open_flags & (O_CREAT | O_TRUNC)) {
 			ksmbd_debug(SMB,
 				    "User does not have write permission\n");
 			rc = -EACCES;
@@ -5944,12 +5944,6 @@ static int smb2_set_info_file(struct ksmbd_work *work, struct ksmbd_file *fp,
 	}
 	case FILE_RENAME_INFORMATION:
 	{
-		if (!test_tree_conn_flag(work->tcon, KSMBD_TREE_CONN_FLAG_WRITABLE)) {
-			ksmbd_debug(SMB,
-				    "User does not have write permission\n");
-			return -EACCES;
-		}
-
 		if (buf_len < sizeof(struct smb2_file_rename_info))
 			return -EINVAL;
 
@@ -5969,12 +5963,6 @@ static int smb2_set_info_file(struct ksmbd_work *work, struct ksmbd_file *fp,
 	}
 	case FILE_DISPOSITION_INFORMATION:
 	{
-		if (!test_tree_conn_flag(work->tcon, KSMBD_TREE_CONN_FLAG_WRITABLE)) {
-			ksmbd_debug(SMB,
-				    "User does not have write permission\n");
-			return -EACCES;
-		}
-
 		if (buf_len < sizeof(struct smb2_file_disposition_info))
 			return -EINVAL;
 
@@ -6036,7 +6024,7 @@ int smb2_set_info(struct ksmbd_work *work)
 {
 	struct smb2_set_info_req *req;
 	struct smb2_set_info_rsp *rsp;
-	struct ksmbd_file *fp;
+	struct ksmbd_file *fp = NULL;
 	int rc = 0;
 	unsigned int id = KSMBD_NO_FID, pid = KSMBD_NO_FID;
 
@@ -6056,6 +6044,13 @@ int smb2_set_info(struct ksmbd_work *work)
 		rsp = smb2_get_msg(work->response_buf);
 	}
 
+	if (!test_tree_conn_flag(work->tcon, KSMBD_TREE_CONN_FLAG_WRITABLE)) {
+		ksmbd_debug(SMB, "User does not have write permission\n");
+		pr_err("User does not have write permission\n");
+		rc = -EACCES;
+		goto err_out;
+	}
+
 	if (!has_file_id(id)) {
 		id = req->VolatileFileId;
 		pid = req->PersistentFileId;