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fix(shadow): fix volumetric shadow heap overflow that corrupted the memory pool - #383
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initMemoryManager() used "sizeof MemoryPoolFactory" and "sizeof DynamicMemoryAllocator". sizeof on a type name needs parentheses; MSVC accepts the short form, GCC does not. The file is only compiled with RTS_GAMEMEMORY_ENABLE=OFF, which RTS_BUILD_OPTION_ASAN turns on, so the AddressSanitizer build failed on Linux. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Is_Valid_Float() and Is_Valid_Double() read the value through an unsigned long pointer. unsigned long is 4 bytes on Windows but 8 bytes on 64-bit Linux, so Is_Valid_Float() read 4 bytes past the float (AddressSanitizer stack-buffer-overflow in W3DProjectedShadowManager::queueDecal), and the "+ 1" in Is_Valid_Double() pointed past the double, so it checked unrelated memory. Copy the bits into uint32_t / uint64_t instead. Is_Valid_Float() returns the same results as before. Is_Valid_Double() now checks the double itself; it has no callers at the moment. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
allocateSilhouette() sized the silhouette edge list as numVertices * 5, but buildSilhouette() adds up to 3 edges (6 indices) per polygon, for example for polygons without neighbors. Meshes with many open edges overflowed the silhouette. The shadow volume is sized from m_maxSilhouetteEntries, so constructVolume() then also wrote one triangle past the volume index buffer. In normal builds this corrupted the headers of the next dmaPool_512 block and crashed later in MemoryPoolSingleBlock::setNextFreeBlock. Size the silhouette as max(numVertices * 5, numPolygons * 6). In SetGeometry(), reallocate when the new geometry needs more entries than are allocated, and drop the shadow volumes of that mesh so that updateMeshVolume() allocates them again with the new size. Found with AddressSanitizer: heap-buffer-overflow in addSilhouetteIndices, constructVolume, Geometry::SetPolygonIndex and RenderDynamicMeshVolume. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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| Check name | Status | Explanation |
|---|---|---|
| Description Check |  |
Check skipped - CodeRabbit’s high-level summary is enabled. |
| Title check | |
The title follows the required Conventional Commits format, uses the valid type fix with the shadow scope, contains no @ symbol, and accurately describes the main volumetric shadow heap-overflow… |
| Linked Issues check | |
Check skipped because no linked issues were found for this pull request. |
| Out of Scope Changes check | |
Check skipped because no linked issues were found for this pull request. |
| Platform Isolation | |
PASS. The pull request adds no Win32, Cocoa, or raw POSIX API. The only change under Core/GameEngine is a portable sizeof syntax correction. The wwmath change uses standard C memcpy and integer types.… |
| Cross-Platform Determinism | |
The pull request does not introduce a Cross-Platform Determinism violation. The changed shadow code uses only integer capacity arithmetic (MAX(numVertices * 5, numPolygons * 6)) and adds no division… |
| Openal / Miniaudio Parity | |
The pull request changes seven files related to memory allocation, floating-point validation, volumetric shadows, and documentation. No OpenAL or MiniAudio files, symbols, or audio backend changes app… |
| Conventional Commit Standards | |
All five non-merge commit subjects in the reviewed range follow Conventional Commits syntax, including valid types and optional scopes. None contains '@'. The PR title also follows the format and cont… |
| No Hardcoded Local Paths / Sensitive Info | |
The pull request adds no personal machine paths, private environment variables, internal URLs, or local workspace paths. Added source and worklog content contains only project-relative include paths, … |
| Ngmp Protocol Integrity | |
The reviewed range changes only memory allocation, floating-point validation, volumetric shadow code, and the worklog. No files under GeneralsOnline/, NextGenMP/, or cmake/ngmp.cmake changed. The diff… |
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Explanation
The title follows the required Conventional Commits format, uses the valid type
fixwith theshadowscope, contains no@symbol, and accurately describes the main volumetric shadow heap-overflow fix.
Full details: Platform Isolation
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Explanation
PASS. The pull request adds no Win32, Cocoa, or raw POSIX API. The only change under Core/GameEngine is a portable sizeof syntax correction. The wwmath change uses standard C memcpy and integer types. Shadow changes are confined to Generals/GeneralsMD GameEngineDevice paths, which are permitted for platform-facing code. Linux, GCC, and ASan references occur only in comments and documentation.
Full details: Cross-Platform Determinism
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Explanation
The pull request does not introduce a Cross-Platform Determinism violation. The changed shadow code uses only integer capacity arithmetic (
MAX(numVertices * 5, numPolygons * 6)) and adds no division, floating-point math, or integer cast. Thewwmath.hchanges use fixed-widthmemcpybit checks for NaN/Inf detection and do not replace deterministic WWMath functions or create an unprotected division before an integer cast. Existing divisions and raw math elsewhere in the files are outside the reviewed diff.
Full details: Openal / Miniaudio Parity
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Explanation
The pull request changes seven files related to memory allocation, floating-point validation, volumetric shadows, and documentation. No OpenAL or MiniAudio files, symbols, or audio backend changes appear in the reviewed diff. Audio parity is therefore not applicable.
Full details: Conventional Commit Standards
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All five non-merge commit subjects in the reviewed range follow Conventional Commits syntax, including valid types and optional scopes. None contains '@'. The PR title also follows the format and contains no '@'.
Full details: No Hardcoded Local Paths / Sensitive Info
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The pull request adds no personal machine paths, private environment variables, internal URLs, or local workspace paths. Added source and worklog content contains only project-relative include paths, build-option text, platform names, and code comments.
Full details: Ngmp Protocol Integrity
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Explanation
The reviewed range changes only memory allocation, floating-point validation, volumetric shadow code, and the worklog. No files under GeneralsOnline/, NextGenMP/, or cmake/ngmp.cmake changed. The diff adds no NGMP, GameSpy, UI-thread, transport, WebSocket, REST, or Win32-networking changes. Therefore, the PR does not introduce a regression covered by NGMP Protocol Integrity.
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Vertices count, polygons too
Silhouette buffers grow to fit
Old mesh shadows clear the way
Float bits take a fixed-width path
Allocations spell out their size
The worklog marks the changes done
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Actionable comments posted: 6
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Inline comments:
Review comments at @Core/Libraries/Source/WWVegas/WWMath/wwmath.h:
- Line 43: Replace the direct stdint.h include in wwmath.h with the repository’s
VC6-compatible stdint_adapter.h so the header uses the existing fixed-width type
compatibility layer.
Review comments at @docs/WORKLOG/2026-10-DIARY.md:
- Line 13: Update the Is_Valid_Double entry in the worklog to state that
incrementing the unsigned long pointer on 64-bit Linux read past the double,
causing an out-of-bounds read. Remove the inaccurate claim that it checked only
the low 32 bits.
Review comments at
@Generals/Code/GameEngineDevice/Source/W3DDevice/GameClient/Shadow/W3DVolumetricShadow.cpp:
- Line 1778: Update the `SetGeometry` loop that calculates `numNewEntries` from
mesh vertex and polygon counts to iterate only through
`geometry->getMeshCount()` for the new geometry, so it does not read
uninitialized unused mesh slots. Handle previously populated slots separately if
needed.
- Line 1761: Update the silhouette-entry capacity calculation and its count
fields, including m_maxSilhouetteEntries and m_numSilhouetteIndices, to use a
type wide enough for the requested capacity; check the arithmetic for overflow
before allocating the entries.
Review comments at
@GeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/Shadow/W3DVolumetricShadow.cpp:
- Line 1866: Limit the capacity calculation in the loop using silhouetteEntries
to meshes below geometry->getMeshCount(), since unused W3DShadowGeometryMesh
slots may have uninitialized polygon counts. Handle any required legacy-slot
behavior separately without reading those uninitialized values.
- Line 1849: Widen m_maxSilhouetteEntries and m_numSilhouetteIndices so they can
represent the required silhouette capacity, and update the capacity calculation
returning MAX(numVertices * 5, numPolygons * 6) to perform arithmetic in that
wider type with overflow checks before allocation.
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📒 Files selected for processing: 7
Core/GameEngine/Source/Common/System/GameMemoryNull.cppCore/Libraries/Source/WWVegas/WWMath/wwmath.hGenerals/Code/GameEngineDevice/Include/W3DDevice/GameClient/W3DVolumetricShadow.hGenerals/Code/GameEngineDevice/Source/W3DDevice/GameClient/Shadow/W3DVolumetricShadow.cppGeneralsMD/Code/GameEngineDevice/Include/W3DDevice/GameClient/W3DVolumetricShadow.hGeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/Shadow/W3DVolumetricShadow.cppdocs/WORKLOG/2026-10-DIARY.md
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…orklog - Widen m_numSilhouetteIndices and m_maxSilhouetteEntries from Short to Int. The silhouette of a mesh with more than 5461 polygons or 6553 vertices needs more than 32767 entries. - SetGeometry() only reads the vertex and polygon counts of meshes below getMeshCount(); the counts of unused slots are not initialized. - wwmath.h includes Precompiled/stdint_adapter.h instead of <stdint.h>, which VC6 does not have. - Correct the Is_Valid_Double description in the worklog: the "+ 1" read past the double, it did not check the low 32 bits. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2 participants
Background
I was playing the ShockWave mod and got a crash. Commits 8dd5be1 and bd0a76b were needed so I could debug the memory issue on Linux with AddressSanitizer. Commit cece709 is the fix for the original crash.
Summary
Fixes a SIGSEGV in
MemoryPoolSingleBlock::setNextFreeBlockon Linux, which happened whileplaying the ShockWave Nuke General challenge. The
dmaPool_512free list was overwritten with16-bit triangle index data, so earlier code had written past the end of its block.
Volumetric shadow overflow (root cause, Generals + GeneralsMD)
allocateSilhouette()sized the silhouette edge list asnumVertices * 5. ButbuildSilhouette()adds up to 3 edges (6 indices) per polygon, for example for polygonswithout neighbors (
addNeighborlessEdges()). Meshes with many open edges overflowed it.Geometryis sized fromm_maxSilhouetteEntries. SoconstructVolume()also wrote one triangle past the volume index buffer, into the header of the next
dmaPool_512block.silhouetteEntries()returnsmax(numVertices * 5, numPolygons * 6).SetGeometry()now reallocates when the new geometry needs more entries than are allocated.Before, it compared vertex counts with the previous geometry. It also drops the shadow volumes
of that mesh, so
updateMeshVolume()creates them again with the new size.ASan build
GameMemoryNull.cppusedsizeof Typewithout parentheses, which GCC rejects. This file isonly built with
RTS_GAMEMEMORY_ENABLE=OFF, for example withRTS_BUILD_OPTION_ASAN=ON.Is_Valid_Float/Is_Valid_Double(wwmath.h)unsigned long*, which is 8 bytes on 64-bit Linux. ASanreported a stack-buffer-overflow read in
Is_Valid_Float.Is_Valid_Doubleonly checked thelow 32 bits. Both now
memcpythe bits intouint32_t/uint64_t.Testing
linux64-deploybuild ofz_generalswithRTS_BUILD_OPTION_ASAN=ONand-fsanitize-recover=address.addSilhouetteIndices,constructVolume,Geometry::SetPolygonIndexandRenderDynamicMeshVolume.ASan reports.
linux64-deploybuild ofg_generalswith the backported shadow fix.Summary by CodeRabbit