restore: don't corrupt stack for a zero-length command-line argument

Given a zero-length directory name, the trailing-slash removal
code would test dir_name[-1], and if it were found to be a slash,
would set it to '\0'.

Reviewed-by: Josef Bacik <josef@redhat.com>

1 files changed, 3 insertions, 5 deletions

diff --git a/restore.c b/restore.c
index 250c9d3c..26748324 100644
--- a/restore.c
+++ b/restore.c
@@ -849,11 +849,9 @@ int main(int argc, char **argv)
 	strncpy(dir_name, argv[optind + 1], 128);
 
 	/* Strip the trailing / on the dir name */
-	while (1) {
-		len = strlen(dir_name);
-		if (dir_name[len - 1] != '/')
-			break;
-		dir_name[len - 1] = '\0';
+	len = strlen(dir_name);
+	while (len && dir_name[--len] == '/') {
+		dir_name[len] = '\0';
 	}
 
 	if (find_dir) {