From: Thiago Rafael Becker <tbecker@redhat.com>
Date: Wed, 5 Apr 2023 10:16:48 -0300
Subject: [PATCH] cifs: sanitize paths in cifs_update_super_prepath.
Git-commit: d19342c6609b67f2ba83b9eccca2777e3687f625
References: bsc#1190317
Patch-mainline: v6.3-rc6

[ematsumiya: adjust patch for pre-fs_context modifications]

After a server reboot, clients are failing to move files with ENOENT.
This is caused by DFS referrals containing multiple separators, which
the server move call doesn't recognize.

v1: Initial patch.
v2: Move prototype to header.

Link: https://bugzilla.redhat.com/show_bug.cgi?id=2182472
Fixes: a31080899d5f ("cifs: sanitize multiple delimiters in prepath")
Actually-Fixes: 24e0a1eff9e2 ("cifs: switch to new mount api")
Reviewed-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Thiago Rafael Becker <tbecker@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
 fs/cifs/cifsproto.h |    1 +
 fs/cifs/connect.c   |   13 +++++++------
 fs/cifs/misc.c      |    2 +-
 3 files changed, 9 insertions(+), 7 deletions(-)

--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -85,6 +85,7 @@ extern void release_mid(struct mid_q_ent
 extern void cifs_wake_up_task(struct mid_q_entry *mid);
 extern int cifs_handle_standard(struct TCP_Server_Info *server,
 				struct mid_q_entry *mid);
+extern char *cifs_sanitize_prepath(char *prepath, gfp_t gfp);
 extern bool cifs_match_ipaddr(struct sockaddr *srcaddr, struct sockaddr *rhs);
 extern int cifs_discard_remaining_data(struct TCP_Server_Info *server);
 extern int cifs_call_async(struct TCP_Server_Info *server,
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1584,13 +1584,14 @@ cifs_parse_smb_version(char *value, stru
  * but there are some bugs that prevent rename from working if there are
  * multiple delimiters.
  *
- * Returns a sanitized duplicate of @path. The caller is responsible for
- * cleaning up the original.
+ * Returns a sanitized duplicate of @path. @gfp indicates the GFP_* flags
+ * for kstrdup.
+ * The caller is responsible for freeing the original.
  */
 #define IS_DELIM(c) ((c) == '/' || (c) == '\\')
-static char *sanitize_path(char *path)
+char *cifs_sanitize_prepath(char *prepath, gfp_t gfp)
 {
-	char *cursor1 = path, *cursor2 = path;
+	char *cursor1 = prepath, *cursor2 = prepath;
 
 	/* skip all prepended delimiters */
 	while (IS_DELIM(*cursor1))
@@ -1612,7 +1613,7 @@ static char *sanitize_path(char *path)
 		cursor2--;
 
 	*(cursor2) = '\0';
-	return kstrdup(path, GFP_KERNEL);
+	return kstrdup(prepath, gfp);
 }
 
 /*
@@ -1667,7 +1668,7 @@ cifs_parse_devname(const char *devname,
 	if (!*pos || !pos)
 		return 0;
 
-	vol->prepath = sanitize_path(pos);
+	vol->prepath = cifs_sanitize_prepath(pos, GFP_KERNEL);
 	if (!vol->prepath)
 		return -ENOMEM;
 
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -1126,7 +1126,7 @@ int cifs_update_super_prepath(struct cif
 	kfree(cifs_sb->prepath);
 
 	if (prefix && *prefix) {
-		cifs_sb->prepath = kstrdup(prefix, GFP_ATOMIC);
+		cifs_sb->prepath = cifs_sanitize_prepath(prefix, GFP_ATOMIC);
 		if (!cifs_sb->prepath)
 			return -ENOMEM;