From d64d0eb9e10691d02bced345ec95c3b3417118a7 Mon Sep 17 00:00:00 2001
From: UnknownShadow200 <unknownshadow200@gmail.com>
Date: Mon, 20 Apr 2020 22:47:22 +1000
Subject: [PATCH] Fix game crashing if using default.png with width < 16 or non
 power of two

---
 src/Drawer2D.c | 26 ++++++++++++++++++++------
 src/Drawer2D.h |  2 +-
 src/Launcher.c |  6 ++++--
 3 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/src/Drawer2D.c b/src/Drawer2D.c
index 3a04d4285..5c5df0205 100644
--- a/src/Drawer2D.c
+++ b/src/Drawer2D.c
@@ -109,9 +109,6 @@ static void CalculateTextWidths(void) {
 	BitmapCol* row;
 	int i, x, y, xx, tileX, tileY;
 
-	/* If 128x256 font bitmap is supplied, treat it as 128x128 */
-	height = min(width, height);
-
 	for (y = 0; y < height; y++) {
 		tileY = y / tileSize;
 		row   = Bitmap_GetRow(&fontBitmap, y);
@@ -139,11 +136,27 @@ static void FreeFontBitmap(void) {
 	Mem_Free(fontBitmap.Scan0);
 }
 
-void Drawer2D_SetFontBitmap(Bitmap* bmp) {
+cc_bool Drawer2D_SetFontBitmap(Bitmap* bmp) {
+	/* If all these cases are not accounted for, end up overwriting memory after tileWidths */
+	if (bmp->Width != bmp->Height) {
+		static const String msg = String_FromConst("&cWidth of default.png must equal its height");
+		Logger_WarnFunc(&msg);
+		return false;
+	} else if (bmp->Width < 16) {
+		static const String msg = String_FromConst("&cdefault.png must be at least 16 pixels wide");
+		Logger_WarnFunc(&msg);
+		return false;
+	} else if (!Math_IsPowOf2(bmp->Width)) {
+		static const String msg = String_FromConst("&cWidth of default.png must be a power of two");
+		Logger_WarnFunc(&msg);
+		return false;
+	}
+
 	FreeFontBitmap();
 	fontBitmap = *bmp;
 	tileSize   = bmp->Width >> LOG2_CHARS_PER_ROW;
 	CalculateTextWidths();
+	return true;
 }
 
 void Font_ReducePadding(struct FontDesc* desc, int scale) {
@@ -683,9 +696,10 @@ static void OnFileChanged(void* obj, struct Stream* src, const String* name) {
 	if ((res = Png_Decode(&bmp, src))) {
 		Logger_Warn2(res, "decoding", name);
 		Mem_Free(bmp.Scan0);
-	} else {
-		Drawer2D_SetFontBitmap(&bmp);
+	} else if (Drawer2D_SetFontBitmap(&bmp)) {
 		Event_RaiseVoid(&ChatEvents.FontChanged);
+	} else {
+		Mem_Free(bmp.Scan0);
 	}
 }
 
diff --git a/src/Drawer2D.h b/src/Drawer2D.h
index 1c63cbc45..fc18d6d52 100644
--- a/src/Drawer2D.h
+++ b/src/Drawer2D.h
@@ -93,7 +93,7 @@ void Drawer2D_ReducePadding_Tex(struct Texture* tex, int point, int scale);
 void Drawer2D_ReducePadding_Height(int* height, int point, int scale);
 /* Sets the bitmap used for drawing bitmapped fonts. (i.e. default.png) */
 /* The bitmap must be square and consist of a 16x16 tile layout. */
-void Drawer2D_SetFontBitmap(Bitmap* bmp);
+cc_bool Drawer2D_SetFontBitmap(Bitmap* bmp);
 
 /* Gets the list of all supported system font names on this platform. */
 void Font_GetNames(StringsBuffer* buffer);
diff --git a/src/Launcher.c b/src/Launcher.c
index 6fe35806e..bc2197f37 100644
--- a/src/Launcher.c
+++ b/src/Launcher.c
@@ -391,9 +391,11 @@ static cc_result Launcher_ProcessZipEntry(const String* path, struct Stream* dat
 
 		if (res) {
 			Logger_Warn(res, "decoding default.png"); return res;
-		} else {
-			Drawer2D_SetFontBitmap(&fontBmp);
+		} else if (Drawer2D_SetFontBitmap(&fontBmp)) {
 			useBitmappedFont = !Options_GetBool(OPT_USE_CHAT_FONT, false);
+		} else {
+			Mem_Free(fontBmp.Scan0);
+			fontBmp.Scan0 = NULL;
 		}
 	} else if (String_CaselessEqualsConst(path, "terrain.png")) {
 		if (dirtBmp.Scan0) return 0;