Fix memory leaks in cifs_do_mount()

BugLink: http://bugs.launchpad.net/bugs/1626112

Fix memory leaks introduced by the patch
fs/cifs: make share unaccessible at root level mountable

Also move allocation of cifs_sb->prepath to cifs_setup_cifs_sb().
Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Tested-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <smfrench@gmail.com>
(backported from commit 4214ebf4)
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

fs/cifs/cifsfs.c

@@ -683,26 +683,22 @@ cifs_do_mount(struct file_system_type *fs_type,
 	cifs_sb->mountdata = kstrndup(data, PAGE_SIZE, GFP_KERNEL);
 	if (cifs_sb->mountdata == NULL) {
 		root = ERR_PTR(-ENOMEM);
-		goto out_cifs_sb;
+		goto out_free;
 	}
 
-	if (volume_info->prepath) {
-		cifs_sb->prepath = kstrdup(volume_info->prepath, GFP_KERNEL);
-		if (cifs_sb->prepath == NULL) {
-			root = ERR_PTR(-ENOMEM);
-			goto out_cifs_sb;
-		}
+	rc = cifs_setup_cifs_sb(volume_info, cifs_sb);
+	if (rc) {
+		root = ERR_PTR(rc);
+		goto out_free;
 	}
 
-	cifs_setup_cifs_sb(volume_info, cifs_sb);
-
 	rc = cifs_mount(cifs_sb, volume_info);
 	if (rc) {
 		if (!(flags & MS_SILENT))
 			cifs_dbg(VFS, "cifs_mount failed w/return code = %d\n",
 				 rc);
 		root = ERR_PTR(rc);
-		goto out_mountdata;
+		goto out_free;
 	}
 
 	mnt_data.vol = volume_info;
@@ -749,9 +745,9 @@ cifs_do_mount(struct file_system_type *fs_type,
 	cifs_cleanup_volume_info(volume_info);
 	return root;
 
-out_mountdata:
+out_free:
+	kfree(cifs_sb->prepath);
 	kfree(cifs_sb->mountdata);
-out_cifs_sb:
 	kfree(cifs_sb);
 out_nls:
 	unload_nls(volume_info->local_nls);

fs/cifs/cifsproto.h

@@ -185,7 +185,7 @@ extern int cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
 extern int cifs_readv_from_socket(struct TCP_Server_Info *server,
 		struct kvec *iov_orig, unsigned int nr_segs,
 		unsigned int to_read);
-extern void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
+extern int cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
 			       struct cifs_sb_info *cifs_sb);
 extern int cifs_match_super(struct super_block *, void *);
 extern void cifs_cleanup_volume_info(struct smb_vol *pvolume_info);

fs/cifs/connect.c

@@ -3254,7 +3254,7 @@ void reset_cifs_unix_caps(unsigned int xid, struct cifs_tcon *tcon,
 	}
 }
 
-void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
+int cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
 			struct cifs_sb_info *cifs_sb)
 {
 	INIT_DELAYED_WORK(&cifs_sb->prune_tlinks, cifs_prune_tlinks);
@@ -3348,6 +3348,14 @@ void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
 
 	if ((pvolume_info->cifs_acl) && (pvolume_info->dynperm))
 		cifs_dbg(VFS, "mount option dynperm ignored if cifsacl mount option supported\n");
+
+	if (pvolume_info->prepath) {
+		cifs_sb->prepath = kstrdup(pvolume_info->prepath, GFP_KERNEL);
+		if (cifs_sb->prepath == NULL)
+			return -ENOMEM;
+	}
+
+	return 0;
 }
 
 static void