ext4: fix memory leak when quota options are specified multiple times

When usrjquota or grpjquota mount options are specified several times,
we leak memory storing the names. Free the memory correctly.
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

fs/ext4/super.c

@@ -1337,6 +1337,7 @@ static int set_qf_name(struct super_block *sb, int qtype, substring_t *args)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	char *qname;
+	int ret = -1;
 
 	if (sb_any_quota_loaded(sb) &&
 		!sbi->s_qf_names[qtype]) {
@@ -1351,23 +1352,26 @@ static int set_qf_name(struct super_block *sb, int qtype, substring_t *args)
 			"Not enough memory for storing quotafile name");
 		return -1;
 	}
-	if (sbi->s_qf_names[qtype] &&
-		strcmp(sbi->s_qf_names[qtype], qname)) {
+	if (sbi->s_qf_names[qtype]) {
+		if (strcmp(sbi->s_qf_names[qtype], qname) == 0)
+			ret = 1;
+		else
 			ext4_msg(sb, KERN_ERR,
-			"%s quota file already specified", QTYPE2NAME(qtype));
-		kfree(qname);
-		return -1;
+				 "%s quota file already specified",
+				 QTYPE2NAME(qtype));
+		goto errout;
 	}
-	sbi->s_qf_names[qtype] = qname;
-	if (strchr(sbi->s_qf_names[qtype], '/')) {
+	if (strchr(qname, '/')) {
 		ext4_msg(sb, KERN_ERR,
 			"quotafile must be on filesystem root");
-		kfree(sbi->s_qf_names[qtype]);
-		sbi->s_qf_names[qtype] = NULL;
-		return -1;
+		goto errout;
 	}
+	sbi->s_qf_names[qtype] = qname;
 	set_opt(sb, QUOTA);
 	return 1;
+errout:
+	kfree(qname);
+	return ret;
 }
 
 static int clear_qf_name(struct super_block *sb, int qtype)
@@ -1381,10 +1385,7 @@ static int clear_qf_name(struct super_block *sb, int qtype)
 			" when quota turned on");
 		return -1;
 	}
-	/*
-	 * The space will be released later when all options are confirmed
-	 * to be correct
-	 */
+	kfree(sbi->s_qf_names[qtype]);
 	sbi->s_qf_names[qtype] = NULL;
 	return 1;
 }
@@ -4593,7 +4594,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 	unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
 	int err = 0;
 #ifdef CONFIG_QUOTA
-	int i;
+	int i, j;
 #endif
 	char *orig_data = kstrdup(data, GFP_KERNEL);
 
@@ -4609,7 +4610,16 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 #ifdef CONFIG_QUOTA
 	old_opts.s_jquota_fmt = sbi->s_jquota_fmt;
 	for (i = 0; i < MAXQUOTAS; i++)
-		old_opts.s_qf_names[i] = sbi->s_qf_names[i];
+		if (sbi->s_qf_names[i]) {
+			old_opts.s_qf_names[i] = kstrdup(sbi->s_qf_names[i],
+							 GFP_KERNEL);
+			if (!old_opts.s_qf_names[i]) {
+				for (j = 0; j < i; j++)
+					kfree(old_opts.s_qf_names[j]);
+				return -ENOMEM;
+			}
+		} else
+			old_opts.s_qf_names[i] = NULL;
 #endif
 	if (sbi->s_journal && sbi->s_journal->j_task->io_context)
 		journal_ioprio = sbi->s_journal->j_task->io_context->ioprio;
@@ -4742,8 +4752,6 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 #ifdef CONFIG_QUOTA
 	/* Release old quota file names */
 	for (i = 0; i < MAXQUOTAS; i++)
-		if (old_opts.s_qf_names[i] &&
-		    old_opts.s_qf_names[i] != sbi->s_qf_names[i])
 		kfree(old_opts.s_qf_names[i]);
 	if (enable_quota) {
 		if (sb_any_quota_suspended(sb))
@@ -4773,8 +4781,6 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 #ifdef CONFIG_QUOTA
 	sbi->s_jquota_fmt = old_opts.s_jquota_fmt;
 	for (i = 0; i < MAXQUOTAS; i++) {
-		if (sbi->s_qf_names[i] &&
-		    old_opts.s_qf_names[i] != sbi->s_qf_names[i])
 		kfree(sbi->s_qf_names[i]);
 		sbi->s_qf_names[i] = old_opts.s_qf_names[i];
 	}