From fb10272f5597f97b1c9c46c8828410688788bde6 Mon Sep 17 00:00:00 2001
From: Fred Gylys-Colwell <fredgc@google.com>
Date: Mon, 1 May 2017 14:49:10 -0700
Subject: [PATCH] OEMCrypto Mock should not downgrade SRM

Merge from Widevine repo of http://go/wvgerrit/26560

With this CL, the modifiable oemcrypto mock will only update the SRM
version number if the new number is greater than or equal to the
current one.

b/37744957

Change-Id: I10721146ca0ce24b1087657e18569a434e5d53b8
---
 .../mock/src/oemcrypto_engine_device_properties_mod.cpp      | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libwvdrmengine/oemcrypto/mock/src/oemcrypto_engine_device_properties_mod.cpp b/libwvdrmengine/oemcrypto/mock/src/oemcrypto_engine_device_properties_mod.cpp
index 9f7551cf..4e37a591 100644
--- a/libwvdrmengine/oemcrypto/mock/src/oemcrypto_engine_device_properties_mod.cpp
+++ b/libwvdrmengine/oemcrypto/mock/src/oemcrypto_engine_device_properties_mod.cpp
@@ -374,6 +374,11 @@ class AndroidModifiableCryptoEngine : public CryptoEngine {
     }
     int new_version = GetOption("srm_load_version", -1);
     if (new_version >= 0) {
+      if (new_version < srm_version_) {
+        LOGE("New SRM version is lower than existing SRM version: %d < %d",
+             new_version, srm_version_);
+        return OEMCrypto_ERROR_INVALID_CONTEXT;
+      }
       srm_version_ = new_version;
       LOGI("OEMCrypto mock told to change SRM version to %d.", srm_version_);
       srm_loaded_ = true;