Backported from: https://github.com/Mbed-TLS/mbedtls/pull/8047 diff --git a/thirdparty/mbedtls/library/entropy_poll.c b/thirdparty/mbedtls/library/entropy_poll.c index 3420616a06..fec2abc2e4 100644 --- a/thirdparty/mbedtls/library/entropy_poll.c +++ b/thirdparty/mbedtls/library/entropy_poll.c @@ -51,32 +51,34 @@ #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) -#if !defined(_WIN32_WINNT) -#define _WIN32_WINNT 0x0400 -#endif #include -#include +#include +#include int mbedtls_platform_entropy_poll(void *data, unsigned char *output, size_t len, size_t *olen) { - HCRYPTPROV provider; ((void) data); *olen = 0; - if (CryptAcquireContext(&provider, NULL, NULL, - PROV_RSA_FULL, CRYPT_VERIFYCONTEXT) == FALSE) { - return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; - } + /* + * BCryptGenRandom takes ULONG for size, which is smaller than size_t on + * 64-bit Windows platforms. Extract entropy in chunks of len (dependent + * on ULONG_MAX) size. + */ + while (len != 0) { + unsigned long ulong_bytes = + (len > ULONG_MAX) ? ULONG_MAX : (unsigned long) len; + + if (!BCRYPT_SUCCESS(BCryptGenRandom(NULL, output, ulong_bytes, + BCRYPT_USE_SYSTEM_PREFERRED_RNG))) { + return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; + } - if (CryptGenRandom(provider, (DWORD) len, output) == FALSE) { - CryptReleaseContext(provider, 0); - return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; + *olen += ulong_bytes; + len -= ulong_bytes; } - CryptReleaseContext(provider, 0); - *olen = len; - return 0; } #else /* _WIN32 && !EFIX64 && !EFI32 */