coverity: #1425764

src/lxc/lxccontainer.c

@@ -1561,15 +1561,24 @@ static bool create_run_template(struct lxc_container *c, char *tpath,
 
 			/* note n2[n2args-1] is NULL */
 			n2[n2args - 5] = "--mapped-uid";
-			snprintf(txtuid, 20, "%d", hostuid_mapped);
+
+			ret = snprintf(txtuid, 20, "%d", hostuid_mapped);
+			if (ret < 0 || ret >= 20) {
+				free(newargv);
+				free(n2);
+				_exit(EXIT_FAILURE);
+			}
+
 			n2[n2args - 4] = txtuid;
 			n2[n2args - 3] = "--mapped-gid";
+
 			ret = snprintf(txtgid, 20, "%d", hostgid_mapped);
 			if (ret < 0 || ret >= 20) {
 				free(newargv);
 				free(n2);
 				_exit(EXIT_FAILURE);
 			}
+
 			n2[n2args - 2] = txtgid;
 			n2[n2args - 1] = NULL;
 			free(newargv);