Fix NULL as mount(2) syscall data parameter

Passing NULL for the mount data should not result in EINVAL.  It
should be treated as if an empty string were passed and succeed.

Signed-off-by: Brian Behlendorf <[email protected]>
Signed-off-by: Ned Bass <[email protected]>
Closes #3771

1 files changed, 24 insertions, 23 deletions

diff --git a/module/zfs/zpl_super.c b/module/zfs/zpl_super.c
index 3edacba46..80cc15725 100644
--- a/module/zfs/zpl_super.c
+++ b/module/zfs/zpl_super.c
@@ -227,8 +227,7 @@ static const match_table_t zpl_tokens = {
 };
 
 static int
-zpl_parse_option(char *option, int token, substring_t *args,
-    zfs_mntopts_t *zmo, boolean_t isremount)
+zpl_parse_option(char *option, int token, substring_t *args, zfs_mntopts_t *zmo)
 {
 	switch (token) {
 	case TOKEN_RO:
@@ -318,32 +317,34 @@ zpl_parse_options(char *osname, char *mntopts, zfs_mntopts_t *zmo,
     boolean_t isremount)
 {
 	zfs_mntopts_t *tmp_zmo;
-	substring_t args[MAX_OPT_ARGS];
-	char *tmp_mntopts, *p;
-	int error, token;
-
-	if (mntopts == NULL)
-		return (-EINVAL);
+	int error;
 
 	tmp_zmo = zfs_mntopts_alloc();
 	tmp_zmo->z_osname = strdup(osname);
-	tmp_mntopts = strdup(mntopts);
-
-	while ((p = strsep(&tmp_mntopts, ",")) != NULL) {
-		if (!*p)
-			continue;
-
-		args[0].to = args[0].from = NULL;
-		token = match_token(p, zpl_tokens, args);
-		error = zpl_parse_option(p, token, args, tmp_zmo, isremount);
-		if (error) {
-			zfs_mntopts_free(tmp_zmo);
-			strfree(tmp_mntopts);
-			return (error);
+
+	if (mntopts) {
+		substring_t args[MAX_OPT_ARGS];
+		char *tmp_mntopts, *p;
+		int token;
+
+		tmp_mntopts = strdup(mntopts);
+
+		while ((p = strsep(&tmp_mntopts, ",")) != NULL) {
+			if (!*p)
+				continue;
+
+			args[0].to = args[0].from = NULL;
+			token = match_token(p, zpl_tokens, args);
+			error = zpl_parse_option(p, token, args, tmp_zmo);
+			if (error) {
+				zfs_mntopts_free(tmp_zmo);
+				strfree(tmp_mntopts);
+				return (error);
+			}
 		}
-	}
 
-	strfree(tmp_mntopts);
+		strfree(tmp_mntopts);
+	}
 
 	if (isremount == B_TRUE) {
 		if (zmo->z_osname)