[PATCH] ext4: Fix memory leak when quota options are specified multiple times

[Chen Gang <gang.chen@xxxxxxxxxxx>]

  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@xxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
---
 fs/ext4/super.c |   48 ++++++++++++++++++++++++++++--------------------
 1 file changed, 28 insertions(+), 20 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c014edd..a4a8ecc 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1351,21 +1351,25 @@ 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)) {
-		ext4_msg(sb, KERN_ERR,
-			"%s quota file already specified", QTYPE2NAME(qtype));
+	if (sbi->s_qf_names[qtype]) {
+		int ret = 1;
+
+		if (strcmp(sbi->s_qf_names[qtype], qname)) {
+			ext4_msg(sb, KERN_ERR,
+				"%s quota file already specified",
+				QTYPE2NAME(qtype));
+			ret = -1;
+		}
 		kfree(qname);
-		return -1;
+		return ret;
 	}
-	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;
+		kfree(qname);
 		return -1;
 	}
+	sbi->s_qf_names[qtype] = qname;
 	set_opt(sb, QUOTA);
 	return 1;
 }
@@ -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;
 }
@@ -4605,7 +4606,18 @@ 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]) {
+				int j;
+
+				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;
@@ -4738,9 +4750,7 @@ 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]);
+		kfree(old_opts.s_qf_names[i]);
 	if (enable_quota) {
 		if (sb_any_quota_suspended(sb))
 			dquot_resume(sb, -1);
@@ -4769,9 +4779,7 @@ restore_opts:
 #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]);
+		kfree(sbi->s_qf_names[i]);
 		sbi->s_qf_names[i] = old_opts.s_qf_names[i];
 	}
 #endif
-- 
1.7.10.4
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