From e7444d0b84a8fd41aa63ecb083e65fd56b32fd38 Mon Sep 17 00:00:00 2001
From: Jon Maloy <jmaloy@redhat.com>
Date: Sun, 23 Jun 2024 14:21:01 -0400
Subject: [PATCH 14/31] SecurityPkg/RngDxe: Conditionally install
 EFI_RNG_PROTOCOL

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: [14/31] bc64d4cad6c30353723d674ef9f10eb10aeb1cac

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

commit 75fb0cfc82376906243386514be0e4067d702117
Author: Pierre Gondois <pierre.gondois@arm.com>
Date:   Thu Nov 24 17:17:55 2022 +0100

    SecurityPkg/RngDxe: Conditionally install EFI_RNG_PROTOCOL

    On Arm platforms, the number of available RNG algorithms is
    dynamically detected and can be 0 in the absence of FEAT_RNG
    and firmware TRNG.
    In this case, the EFI_RNG_PROTOCOL should not be installed to
    prevent from installing an empty protocol.

    Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
    [ardb: return EFI_REQUEST_UNLOAD_IMAGE instead of an error]
    Reviewed-by: Ard Biesheuvel <ardb@kernel.org>

Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
 .../RandomNumberGenerator/RngDxe/RngDxe.c     | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.c b/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.c
index cc2ddfcc06..55e8dd49d0 100644
--- a/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.c
+++ b/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.c
@@ -63,6 +63,18 @@ RngDriverEntry (
   EFI_STATUS    Status;
   EFI_HANDLE    Handle;
 
+  //
+  // Get the list of available algorithm.
+  //
+  Status = GetAvailableAlgorithms ();
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  if (mAvailableAlgoArrayCount == 0) {
+    return EFI_REQUEST_UNLOAD_IMAGE;
+  }
+
   //
   // Install UEFI RNG (Random Number Generator) Protocol
   //
@@ -74,13 +86,10 @@ RngDriverEntry (
                   NULL
                   );
   if (EFI_ERROR (Status)) {
-    return Status;
+    FreeAvailableAlgorithms ();
   }
 
-  //
-  // Get the list of available algorithm.
-  //
-  return GetAvailableAlgorithms ();
+  return Status;
 }
 
 /**
-- 
2.39.3