add guard for size_t underflow

2026-05-12 11:18:11 -07:00 · 2026-03-24 14:21:09 +07:00
parent 0d63e53a77
commit c62b9e0480
1 changed files with 9 additions and 0 deletions
@@ -600,6 +600,15 @@ void *mifare_cryto_postprocess_data(desfiretag_t tag, void *data, size_t *nbytes

                    if ((communication_settings & MAC_VERIFY) == MAC_VERIFY) {

+                        if (*nbytes < key_macing_length(key)) {
+                            *nbytes = -1;
+                            res = NULL;
+#ifdef WITH_DEBUG
+                            Dbprintf("No room for MAC!");
+#endif
+                            break;
+                        }
+
                        *nbytes -= key_macing_length(key);

                        if (*nbytes == 0) {