From a5f0aab16397f6e46f4b5c50e35347ce678cfbb0 Mon Sep 17 00:00:00 2001
From: Kelsey Gilbert <kelsey.gilbert@mozilla.com>
Date: Tue, 4 Jun 2024 15:37:29 -0700
Subject: [PATCH] Add GLSL variable byte size limits to ShBuiltInResources.

---
 include/GLSLANG/ShaderLang.h             |  5 +++++
 src/compiler/translator/Compiler.cpp     |  3 +++
 src/compiler/translator/ParseContext.cpp | 20 +++++++-------------
 src/compiler/translator/ShaderLang.cpp   |  6 ++++++
 4 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/include/GLSLANG/ShaderLang.h b/include/GLSLANG/ShaderLang.h
index 200eaac2c5..135daac147 100644
--- a/include/GLSLANG/ShaderLang.h
+++ b/include/GLSLANG/ShaderLang.h
@@ -764,6 +764,11 @@ struct ShBuiltInResources
     // ANGLE_shader_pixel_local_storage.
     int MaxPixelLocalStoragePlanes;
     int MaxCombinedDrawBuffersAndPixelLocalStoragePlanes;
+
+    // Variable size limits for webgl-mode validation.
+    size_t MaxVariableSizeInBytes;
+    size_t MaxPrivateVariableSizeInBytes;
+    size_t MaxTotalPrivateVariableSizeInBytes;
 };
 
 //
diff --git a/src/compiler/translator/Compiler.cpp b/src/compiler/translator/Compiler.cpp
index 9ba125a178..ebf0bd49c6 100644
--- a/src/compiler/translator/Compiler.cpp
+++ b/src/compiler/translator/Compiler.cpp
@@ -1511,6 +1511,9 @@ void TCompiler::setResourceString()
         << ":MaxFragmentImageUniforms:" << mResources.MaxFragmentImageUniforms
         << ":MaxComputeImageUniforms:" << mResources.MaxComputeImageUniforms
         << ":MaxCombinedImageUniforms:" << mResources.MaxCombinedImageUniforms
+        << ":MaxVariableSizeInBytes:" << mResources.MaxVariableSizeInBytes
+        << ":MaxPrivateVariableSizeInBytes:" << mResources.MaxPrivateVariableSizeInBytes
+        << ":MaxTotalPrivateVariableSizeInBytes:" << mResources.MaxTotalPrivateVariableSizeInBytes
         << ":MaxCombinedShaderOutputResources:" << mResources.MaxCombinedShaderOutputResources
         << ":MaxComputeWorkGroupCountX:" << mResources.MaxComputeWorkGroupCount[0]
         << ":MaxComputeWorkGroupCountY:" << mResources.MaxComputeWorkGroupCount[1]
diff --git a/src/compiler/translator/ParseContext.cpp b/src/compiler/translator/ParseContext.cpp
index 9852c0c9cd..efd6e436ac 100644
--- a/src/compiler/translator/ParseContext.cpp
+++ b/src/compiler/translator/ParseContext.cpp
@@ -45,15 +45,6 @@ namespace
 {
 const int kWebGLMaxStructNesting = 4;
 
-// Arbitrarily enforce that all types declared with a size in bytes of over 2 GB will cause
-// compilation failure.
-//
-// For local and global variables, the limit is much lower (64KB) as that much memory won't fit in
-// the GPU registers anyway.
-constexpr size_t kWebGLMaxVariableSizeInBytes        = static_cast<size_t>(2) * 1024 * 1024 * 1024;
-constexpr size_t kWebGLMaxPrivateVariableSizeInBytes = static_cast<size_t>(64) * 1024;
-constexpr size_t kWebGLMaxTotalPrivateVariableSizeInBytes = static_cast<size_t>(16) * 1024 * 1024;
-
 // The 1024 character identifier limit, `-2` for the `_u`
 constexpr size_t kMaxAvailableIdentifierLength = 1022;
 
@@ -1755,7 +1746,8 @@ bool TParseContext::checkVariableSize(const TSourceLoc &line,
     const size_t variableSize =
         CalculateVariableSize(type, type->isInterfaceBlock() || type->getQualifier() == EvqUniform)
             .ValueOrDefault(std::numeric_limits<size_t>::max());
-    if (variableSize > kWebGLMaxVariableSizeInBytes)
+    if (mResources.MaxVariableSizeInBytes &&
+        variableSize > mResources.MaxVariableSizeInBytes)
     {
         error(line, "Size of declared variable exceeds implementation-defined limit", identifier);
         return false;
@@ -1799,7 +1791,8 @@ bool TParseContext::checkVariableSize(const TSourceLoc &line,
         case EvqPerVertexIn:
         case EvqPerVertexOut:
 
-            if (variableSize > kWebGLMaxPrivateVariableSizeInBytes)
+            if (mResources.MaxPrivateVariableSizeInBytes &&
+                variableSize > mResources.MaxPrivateVariableSizeInBytes)
             {
                 error(line,
                       "Size of declared private variable exceeds implementation-defined limit",
@@ -10401,8 +10394,9 @@ bool TParseContext::postParseChecks()
 
     if (mCompileOptions.rejectWebglShadersWithLargeVariables)
     {
-        if (mTotalPrivateVariablesSize.ValueOrDefault(std::numeric_limits<size_t>::max()) >
-            kWebGLMaxTotalPrivateVariableSizeInBytes)
+        if (mResources.MaxTotalPrivateVariableSizeInBytes &&
+            mTotalPrivateVariablesSize.ValueOrDefault(std::numeric_limits<size_t>::max()) >
+                mResources.MaxTotalPrivateVariableSizeInBytes)
         {
             error(TSourceLoc{},
                   "Total size of declared private variables exceeds implementation-defined limit",
diff --git a/src/compiler/translator/ShaderLang.cpp b/src/compiler/translator/ShaderLang.cpp
index 6477eef68e..ebcb1c050e 100644
--- a/src/compiler/translator/ShaderLang.cpp
+++ b/src/compiler/translator/ShaderLang.cpp
@@ -363,6 +363,12 @@ void InitBuiltInResources(ShBuiltInResources *resources)
     resources->MaxTessEvaluationUniformBlocks        = 12;
 
     resources->MaxSamples = 4;
+
+    // Prevent unrealistically large WebGL variable sizes. These defaults match the current parser
+    // limits while allowing embedders to override them.
+    resources->MaxVariableSizeInBytes             = static_cast<size_t>(2) * 1024 * 1024 * 1024;
+    resources->MaxPrivateVariableSizeInBytes      = static_cast<size_t>(64) * 1024;
+    resources->MaxTotalPrivateVariableSizeInBytes = static_cast<size_t>(16) * 1024 * 1024;
 }
 
 //
-- 
2.54.0