commit dbce1f890a8a4b529f67850f8878fe816d7b7f69
author Olli Etuaho <oetuaho@nvidia.com> Wed Sep 19 15:32:17 2018 +0300
committer Commit Bot <commit-bot@chromium.org> Wed Sep 19 18:30:59 2018 +0000
tree 2c4f5ab0a647cb28a632afb0e9ef1d2c98b2920b
parent bf7cfbea4b926add90ed892b06b5ec2e37c655f6

Fix trying to clear nonexistent FBO attachments

The D3D11 backend used to crash to a null pointer dereference if a
glClearBuffer call was done on a nonexistent depth or stencil
attachment. Validate for these conditions so that the backend can't
crash in this case.

BUG=angleproject:2827
TEST=angle_end2end_tests

Change-Id: Iecee78d213d11d492d52f246b4b068e8b6f34244
Reviewed-on: https://chromium-review.googlesource.com/1233675
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>

src/libANGLE/Context.cpp

diff --git a/src/libANGLE/Context.cpp b/src/libANGLE/Context.cpp
index cb1c678..f9b1fe7 100644
--- a/src/libANGLE/Context.cpp
+++ b/src/libANGLE/Context.cpp
@@ -3534,6 +3534,11 @@
 
 void Context::clearBufferfv(GLenum buffer, GLint drawbuffer, const GLfloat *values)
 {
+    if (buffer == GL_DEPTH && !getGLState().getDrawFramebuffer()->getDepthbuffer())
+    {
+        // It's not an error to try to clear a non-existent depth buffer, but it's a no-op.
+        return;
+    }
     ANGLE_CONTEXT_TRY(prepareForClearBuffer(buffer, drawbuffer));
     ANGLE_CONTEXT_TRY(
         mGLState.getDrawFramebuffer()->clearBufferfv(this, buffer, drawbuffer, values));
@@ -3548,6 +3553,11 @@
 
 void Context::clearBufferiv(GLenum buffer, GLint drawbuffer, const GLint *values)
 {
+    if (buffer == GL_STENCIL && !getGLState().getDrawFramebuffer()->getStencilbuffer())
+    {
+        // It's not an error to try to clear a non-existent stencil buffer, but it's a no-op.
+        return;
+    }
     ANGLE_CONTEXT_TRY(prepareForClearBuffer(buffer, drawbuffer));
     ANGLE_CONTEXT_TRY(
         mGLState.getDrawFramebuffer()->clearBufferiv(this, buffer, drawbuffer, values));