oberthur: One more overlooked buffer overflow

Thanks oss-fuzz

https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=32202

Author: Jakuje

src/libopensc/pkcs15-oberthur.c

@@ -609,7 +609,10 @@ sc_pkcs15emu_oberthur_add_pubkey(struct sc_pkcs15_card *p15card,
 		LOG_TEST_RET(ctx, SC_ERROR_UNKNOWN_DATA_RECEIVED, "Failed to add public key: no 'Label'");
 	}
 	len = *(info_blob + offs + 1) + *(info_blob + offs) * 0x100;
-	if (len)   {
+	if (offs + 2 + len > info_len) {
+		free(info_blob);
+		LOG_TEST_RET(ctx, SC_ERROR_INVALID_DATA, "Failed to add public key: invalid 'Label' length");
+	} else if (len) {
 		if (len > sizeof(key_obj.label) - 1)
 			len = sizeof(key_obj.label) - 1;
 		memcpy(key_obj.label, info_blob + offs + 2, len);