commit 46eee0002ff84ec0231c45dfd3d5241ac6aa88bd
author Pyry Haulos <phaulos@google.com> Thu Sep 03 08:41:09 2015 -0700
committer The Android Automerger <android-build@google.com> Thu Oct 01 15:24:40 2015 -0700
tree 0fa69f0b39a3f31c18a01ef64a5e23bf7790baea
parent c3084e996cd4f69f84b54fff9eaf7a63b69f89d1

Fix out-of-bounds buffer access in tese ShaderExecutor

Tessellation evaluation shader executor was accessing input and output
buffers one element out of bounds at the end. In addition elements
1..N-1 were evaluated twice unnecessarily.

Bug: 23684915
Change-Id: I1c187b506d36befe05b21222a7006e84b812ceca

modules/glshared/glsShaderExecUtil.cpp

diff --git a/modules/glshared/glsShaderExecUtil.cpp b/modules/glshared/glsShaderExecUtil.cpp
index fad4d71..9e324fd 100644
--- a/modules/glshared/glsShaderExecUtil.cpp
+++ b/modules/glshared/glsShaderExecUtil.cpp
@@ -1480,7 +1480,7 @@
 
 	src << "void main (void)\n{\n"
 		<< "\tgl_Position = vec4(gl_TessCoord.x, 0.0, 0.0, 1.0);\n"
-		<< "\thighp uint invocationId = uint(gl_PrimitiveID) + (gl_TessCoord.x > 0.5 ? 1u : 0u);\n";
+		<< "\thighp uint invocationId = uint(gl_PrimitiveID)*2u + (gl_TessCoord.x > 0.5 ? 1u : 0u);\n";
 
 	generateExecBufferIo(src, shaderSpec, "invocationId");
 
@@ -1523,7 +1523,7 @@
 
 	// Render patches
 	gl.patchParameteri(GL_PATCH_VERTICES, 2);
-	gl.drawArrays(GL_PATCHES, 0, 2*alignedValues);
+	gl.drawArrays(GL_PATCHES, 0, alignedValues);
 
 	// Read back data
 	readOutputBuffer(outputs, numValues);