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bugfix(w3ddevice): Prevent crashes and out-of-bounds access in W3DTerrainTracks #500

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Merged
x64-dev merged 1 commit into from
May 7, 2026
Merged

bugfix(w3ddevice): Prevent crashes and out-of-bounds access in W3DTerrainTracks #500

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45 changes: 38 additions & 7 deletions Core/GameEngineDevice/Source/W3DDevice/GameClient/W3DTerrainTracks.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -823,8 +823,24 @@ Try improving the fit to vertical surfaces like cliffs.
//check if there is anything to draw and fill vertex buffer
if (m_edgesToFlush >= 2)
{
// Guard against a null vertex buffer (e.g. if ReleaseResources() was called
// without a matching ReAcquireResources() during a device reset).
if (!m_vertexBuffer)
{
m_edgesToFlush = 0;
return;
}

DX8VertexBufferClass::WriteLockClass lockVtxBuffer(m_vertexBuffer);
VertexFormatXYZDUV1 *verts = (VertexFormatXYZDUV1*)lockVtxBuffer.Get_Vertex_Array();

// Guard against a failed buffer lock returning a null pointer.
if (!verts)
{
m_edgesToFlush = 0;
return;
}

trackStartIndex=0;

mod=m_usedModules;
Expand All @@ -835,9 +851,17 @@ Try improving the fit to vertical surfaces like cliffs.
Vector3 *endPoint;
Vector2 *endPointUV;

if (mod->m_activeEdgeCount >= 2 && mod->Is_Really_Visible())
// Clamp activeEdgeCount to m_maxTankTrackEdges to prevent writing past the
// end of the vertex buffer when m_maxTankTrackEdges was reduced (e.g. by a
// graphics-detail change) while tracks still hold edges from the old, larger
// limit. This also keeps index within the fixed-size m_edges[] array.
Int activeEdgeCount = mod->m_activeEdgeCount;
if (activeEdgeCount > m_maxTankTrackEdges)
activeEdgeCount = m_maxTankTrackEdges;

if (activeEdgeCount >= 2 && mod->Is_Really_Visible())
{
for (i=0,index=mod->m_bottomIndex; i<mod->m_activeEdgeCount; i++,index++)
for (i=0,index=mod->m_bottomIndex; i<activeEdgeCount; i++,index++)
{
if (index >= m_maxTankTrackEdges)
index=0;
Expand All @@ -847,10 +871,10 @@ Try improving the fit to vertical surfaces like cliffs.

distanceFade=1.0f;

if ((mod->m_activeEdgeCount -1 -i) >= m_maxTankTrackOpaqueEdges)// && i < (MAX_PER_TRACK_EDGE_COUNT-FORCE_FADE_AT_EDGE))
if ((activeEdgeCount -1 -i) >= m_maxTankTrackOpaqueEdges)// && i < (MAX_PER_TRACK_EDGE_COUNT-FORCE_FADE_AT_EDGE))
{ //we're getting close to the limit on the number of track pieces allowed
//so force it to fade out.
distanceFade=1.0f-(float)((mod->m_activeEdgeCount -i)-m_maxTankTrackOpaqueEdges)/numFadedEdges;
distanceFade=1.0f-(float)((activeEdgeCount -i)-m_maxTankTrackOpaqueEdges)/numFadedEdges;
}

distanceFade *= mod->m_edges[index].alpha; //adjust fade with distance from start of track
Expand Down Expand Up @@ -898,13 +922,20 @@ Try improving the fit to vertical surfaces like cliffs.
DX8Wrapper::Set_Transform(D3DTS_WORLD,mod->Transform);
while (mod)
{
if (mod->m_activeEdgeCount >= 2 && mod->Is_Really_Visible())
// Use the same clamped edge count as the vertex-fill pass above so that
// trackStartIndex stays consistent and we don't read past the index buffer
// (which is only allocated for m_maxTankTrackEdges-1 segments).
Int activeEdgeCount = mod->m_activeEdgeCount;
if (activeEdgeCount > m_maxTankTrackEdges)
activeEdgeCount = m_maxTankTrackEdges;

if (activeEdgeCount >= 2 && mod->Is_Really_Visible())
{
DX8Wrapper::Set_Texture(0,mod->m_stageZeroTexture);
DX8Wrapper::Set_Index_Buffer_Index_Offset(trackStartIndex);
DX8Wrapper::Draw_Triangles( 0,(mod->m_activeEdgeCount-1)*2, 0, mod->m_activeEdgeCount*2);
DX8Wrapper::Draw_Triangles( 0,(activeEdgeCount-1)*2, 0, activeEdgeCount*2);

trackStartIndex += mod->m_activeEdgeCount*2;
trackStartIndex += activeEdgeCount*2;
}
mod=mod->m_nextSystem;
}
Expand Down
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