From 5ecff99edc9c342987ef59156c2358a4c24ce9b5 Mon Sep 17 00:00:00 2001
From: Mounir IDRASSI <mounir.idrassi@idrix.fr>
Date: Wed, 30 Oct 2019 08:45:01 +0100
Subject: Add check for buggy RDRAND (AMD Ryzen CPU case) even if we always use
 RDSEED instead of RDRAND when RDSEED is available (which is the case on
 modern CPUs)

---
 src/Crypto/cpu.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'src/Crypto')

diff --git a/src/Crypto/cpu.c b/src/Crypto/cpu.c
index 62574983..33a9815e 100644
--- a/src/Crypto/cpu.c
+++ b/src/Crypto/cpu.c
@@ -2,6 +2,7 @@
 
 #include "cpu.h"
 #include "misc.h"
+#include "rdrand.h"
 
 #ifndef EXCEPTION_EXECUTE_HANDLER
 #define EXCEPTION_EXECUTE_HANDLER 1
@@ -387,6 +388,18 @@ void DetectX86Features()
 		}
 	}
 
+	/* Add check fur buggy RDRAND (AMD Ryzen case) even if we always use RDSEED instead of RDRAND when RDSEED available */
+	if (g_hasRDRAND)
+	{
+		if (	RDRAND_getBytes ((unsigned char*) cpuid, sizeof (cpuid))
+			&&	(cpuid[0] == 0xFFFFFFFF) &&	(cpuid[1] == 0xFFFFFFFF)
+			&&	(cpuid[2] == 0xFFFFFFFF) &&	(cpuid[3] == 0xFFFFFFFF)
+			)
+		{
+			g_hasRDRAND = 0;
+		}
+	}
+
 	if (!g_cacheLineSize)
 		g_cacheLineSize = CRYPTOPP_L1_CACHE_LINE_SIZE;
 
-- 
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