From 68682d75b5323ebf45d662dd0d1de563442d147f Mon Sep 17 00:00:00 2001
From: Kim Kulling <kimkulling@users.noreply.github.com>
Date: Fri, 10 Dec 2021 08:39:21 +0100
Subject: [PATCH 1/2] Fix nullptr dereferencing from std::shared_ptr

- Finding from fuzzer
- closes https://github.com/assimp/assimp/issues/4237
---
 code/AssetLib/DXF/DXFLoader.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/code/AssetLib/DXF/DXFLoader.cpp b/code/AssetLib/DXF/DXFLoader.cpp
index 3b20678ad..2f1aa6961 100644
--- a/code/AssetLib/DXF/DXFLoader.cpp
+++ b/code/AssetLib/DXF/DXFLoader.cpp
@@ -378,6 +378,11 @@ void DXFImporter::ExpandBlockReferences(DXF::Block& bl,const DXF::BlockMap& bloc
         const DXF::Block& bl_src = *(*it).second;
 
         for (std::shared_ptr<const DXF::PolyLine> pl_in : bl_src.lines) {
+            if (!pl_in) {
+                ASSIMP_LOG_ERROR("DXF: PolyLine instance is nullptr, skipping.");
+                continue;
+            }
+            
             std::shared_ptr<DXF::PolyLine> pl_out = std::shared_ptr<DXF::PolyLine>(new DXF::PolyLine(*pl_in));
 
             if (bl_src.base.Length() || insert.scale.x!=1.f || insert.scale.y!=1.f || insert.scale.z!=1.f || insert.angle || insert.pos.Length()) {

From 33c676227233c3b543df53284e905781dbf62c10 Mon Sep 17 00:00:00 2001
From: Kim Kulling <kimkulling@users.noreply.github.com>
Date: Fri, 10 Dec 2021 14:32:45 +0100
Subject: [PATCH 2/2] Update HMPLoader.cpp

- Fix possible division by zero
- closes https://github.com/assimp/assimp/issues/4235
---
 code/AssetLib/HMP/HMPLoader.cpp | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/code/AssetLib/HMP/HMPLoader.cpp b/code/AssetLib/HMP/HMPLoader.cpp
index 661e4d1b2..0bc152680 100644
--- a/code/AssetLib/HMP/HMPLoader.cpp
+++ b/code/AssetLib/HMP/HMPLoader.cpp
@@ -473,16 +473,22 @@ void HMPImporter::ReadFirstSkin(unsigned int iNumSkins, const unsigned char *szC
 
 // ------------------------------------------------------------------------------------------------
 // Generate proepr texture coords
-void HMPImporter::GenerateTextureCoords(
-        const unsigned int width, const unsigned int height) {
+void HMPImporter::GenerateTextureCoords(const unsigned int width, const unsigned int height) {
     ai_assert(nullptr != pScene->mMeshes);
     ai_assert(nullptr != pScene->mMeshes[0]);
     ai_assert(nullptr != pScene->mMeshes[0]->mTextureCoords[0]);
 
     aiVector3D *uv = pScene->mMeshes[0]->mTextureCoords[0];
-
-    const float fY = (1.0f / height) + (1.0f / height) / (height - 1);
-    const float fX = (1.0f / width) + (1.0f / width) / (width - 1);
+    if (uv == nullptr) {
+        return;
+    }
+    
+    if (height == 0.0f || width == 0.0) {
+        return;
+    }
+    
+    const float fY = (1.0f / height) + (1.0f / height) / height;
+    const float fX = (1.0f / width) + (1.0f / width) / width;
 
     for (unsigned int y = 0; y < height; ++y) {
         for (unsigned int x = 0; x < width; ++x, ++uv) {