edk2/edk2-SecurityPkg-RngDxe-Correctly-update-mAvailableAlgoAr.patch

From b9a937603080bfada6c224a6e9da046a8a33f868 Mon Sep 17 00:00:00 2001
From: Jon Maloy <jmaloy@redhat.com>
Date: Sun, 23 Jun 2024 14:18:18 -0400
Subject: [PATCH 13/31] SecurityPkg/RngDxe: Correctly update
 mAvailableAlgoArrayCount

RH-Author: Jon Maloy <jmaloy@redhat.com>
RH-MergeRequest: 77: UINT32 overflow in S3 ResumeCount and Pixiefail fixes
RH-Jira: RHEL-21854 RHEL-21856 RHEL-40099
RH-Acked-by: Gerd Hoffmann <None>
RH-Commit: [13/31] 3e06e270cad90038537305a4cb7828fcc45251fb

JIRA: https://issues.redhat.com/browse/RHEL-21856
Upstream: Merged
CVE: CVE-2023-45237

commit bfb574db110899471fe09db819587b3151c7b7b5
Author: Pierre Gondois <pierre.gondois@arm.com>
Date:   Thu Nov 24 17:17:54 2022 +0100

    SecurityPkg/RngDxe: Correctly update mAvailableAlgoArrayCount

    mAvailableAlgoArrayCount holds the count of available RNG algorithms.
    In a following patch, its value will be used to prevent the
    EFI_RNG_PROTOCOL to be installed if no RNG algorithm is available.

    Correctly set/reset the value for all implementations.

    Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
    Reviewed-by: Ard Biesheuvel <ardb@kernel.org>

Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
 .../RandomNumberGenerator/RngDxe/ArmRngDxe.c     |  1 +
 .../RandomNumberGenerator/RngDxe/Rand/RngDxe.c   | 16 ++++++++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c b/SecurityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c
index 5e7d9ef681..0e44d0c931 100644
--- a/SecurityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c
+++ b/SecurityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c
@@ -40,6 +40,7 @@ FreeAvailableAlgorithms (
   VOID
   )
 {
+  mAvailableAlgoArrayCount = 0;
   FreePool (mAvailableAlgoArray);
   return;
 }
diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RngDxe.c b/SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RngDxe.c
index 7caa64a4ff..149de875ce 100644
--- a/SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RngDxe.c
+++ b/SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RngDxe.c
@@ -26,6 +26,11 @@
 
 #include "RngDxeInternals.h"
 
+//
+// Count of Rng algorithms.
+//
+#define RNG_ALGORITHM_COUNT  2
+
 /** Allocate and initialize mAvailableAlgoArray with the available
     Rng algorithms. Also update mAvailableAlgoArrayCount.
 
@@ -38,6 +43,13 @@ GetAvailableAlgorithms (
   VOID
   )
 {
+
+  UINT64  RngTest;
+
+  if (GetRandomNumber64 (&RngTest)) {
+    mAvailableAlgoArrayCount = RNG_ALGORITHM_COUNT;
+  }
+
   return EFI_SUCCESS;
 }
 
@@ -49,6 +61,7 @@ FreeAvailableAlgorithms (
   VOID
   )
 {
+  mAvailableAlgoArrayCount = 0;
   return;
 }
 
@@ -159,13 +172,12 @@ RngGetInfo (
   )
 {
   UINTN RequiredSize;
-  EFI_RNG_ALGORITHM *CpuRngSupportedAlgorithm;
 
   if ((This == NULL) || (RNGAlgorithmListSize == NULL)) {
     return EFI_INVALID_PARAMETER;
   }
 
-  RequiredSize = 2 * sizeof (EFI_RNG_ALGORITHM);
+  RequiredSize = RNG_ALGORITHM_COUNT * sizeof (EFI_RNG_ALGORITHM);
 
   if (*RNGAlgorithmListSize < RequiredSize) {
     *RNGAlgorithmListSize = RequiredSize;
-- 
2.39.3