Fix potential bad access in LinkProgram.

src/libANGLE/Program.cpp

@@ -1049,9 +1049,16 @@ Error Program::link(const gl::Context *context)
     double startTime = platform->currentTime(platform);
 
     unlink();
+    mInfoLog.reset();
+
+    // Validate we have properly attached shaders before checking the cache.
+    if (!linkValidateShaders(context, mInfoLog))
+    {
+        return NoError();
+    }
 
     ProgramHash programHash;
-    auto *cache = context->getMemoryProgramCache();
+    MemoryProgramCache *cache = context->getMemoryProgramCache();
     if (cache)
     {
         ANGLE_TRY_RESULT(cache->getProgram(context, this, &mState, &programHash), mLinked);
@@ -1068,12 +1075,9 @@ Error Program::link(const gl::Context *context)
 
     // Cache load failed, fall through to normal linking.
     unlink();
-    mInfoLog.reset();
 
-    if (!linkValidateShaders(context, mInfoLog))
-    {
-        return NoError();
-    }
+    // Re-link shaders after the unlink call.
+    ASSERT(linkValidateShaders(context, mInfoLog));
 
     if (mState.mAttachedComputeShader)
     {
@@ -1284,6 +1288,7 @@ void Program::unlink()
     mValidated = false;
 
     mLinked = false;
+    mInfoLog.reset();
 }
 
 bool Program::isLinked() const

src/tests/egl_tests/EGLProgramCacheControlTest.cpp

@@ -13,7 +13,7 @@
 using namespace angle;
 
 constexpr EGLint kEnabledCacheSize = 0x10000;
-constexpr char kEGLExtName[]       = "EGL_ANGLE_program_cache_control ";
+constexpr char kEGLExtName[]       = "EGL_ANGLE_program_cache_control";
 
 void TestCacheProgram(PlatformMethods *platform,
                       const ProgramKeyType &key,
@@ -239,4 +239,24 @@ TEST_P(EGLProgramCacheControlTest, SaveAndReload)
     EXPECT_TRUE(mCachedBinary.empty());
 }
 
+// Tests that trying to link a program without correct shaders doesn't buggily call the cache.
+TEST_P(EGLProgramCacheControlTest, LinkProgramWithBadShaders)
+{
+    ANGLE_SKIP_TEST_IF(!extensionAvailable());
+
+    GLuint shader = glCreateShader(GL_FRAGMENT_SHADER);
+
+    GLuint program = glCreateProgram();
+    glAttachShader(program, shader);
+    glLinkProgram(program);
+
+    GLint linkStatus = 0;
+    glGetProgramiv(program, GL_LINK_STATUS, &linkStatus);
+    EXPECT_GL_FALSE(linkStatus);
+    EXPECT_GL_NO_ERROR();
+
+    glDeleteShader(shader);
+    glDeleteProgram(program);
+}
+
 ANGLE_INSTANTIATE_TEST(EGLProgramCacheControlTest, ES2_D3D9(), ES2_D3D11(), ES2_OPENGL());