sandbox: avoid memory leak in os_dirent_ls

Realloc does not free the old memory area if it fails.

Identified by cppcheck.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

arch/sandbox/cpu/os.c

@@ -319,6 +319,7 @@ int os_dirent_ls(const char *dirname, struct os_dirent_node **headp)
 	DIR *dir;
 	int ret;
 	char *fname;
+	char *old_fname;
 	int len;
 	int dirlen;
 
@@ -344,16 +345,23 @@ int os_dirent_ls(const char *dirname, struct os_dirent_node **headp)
 			break;
 		}
 		next = malloc(sizeof(*node) + strlen(entry->d_name) + 1);
-		if (dirlen + strlen(entry->d_name) > len) {
-			len = dirlen + strlen(entry->d_name);
-			fname = realloc(fname, len);
-		}
-		if (!next || !fname) {
-			free(next);
+		if (!next) {
 			os_dirent_free(head);
 			ret = -ENOMEM;
 			goto done;
 		}
+		if (dirlen + strlen(entry->d_name) > len) {
+			len = dirlen + strlen(entry->d_name);
+			old_fname = fname;
+			fname = realloc(fname, len);
+			if (!fname) {
+				free(old_fname);
+				free(next);
+				os_dirent_free(head);
+				ret = -ENOMEM;
+				goto done;
+			}
+		}
 		next->next = NULL;
 		strcpy(next->name, entry->d_name);
 		switch (entry->d_type) {