From a173275afa9864463e7aa4d748960a31cd7b87aa Mon Sep 17 00:00:00 2001
From: Lucas CHOLLET <lucas.chollet@free.fr>
Date: Mon, 17 Jul 2023 00:22:11 -0400
Subject: [PATCH] LibGfx/PNG: Reject files that doesn't start with a IHDr chunk

---
 Userland/Libraries/LibGfx/ImageFormats/PNGLoader.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Userland/Libraries/LibGfx/ImageFormats/PNGLoader.cpp b/Userland/Libraries/LibGfx/ImageFormats/PNGLoader.cpp
index 998e0673ab..07bc7df07d 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/PNGLoader.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/PNGLoader.cpp
@@ -1212,6 +1212,10 @@ static ErrorOr<void> process_chunk(Streamer& streamer, PNGLoadingContext& contex
 
     if (chunk_type == "IHDR"sv)
         return process_IHDR(chunk_data, context);
+
+    if (context.state < PNGLoadingContext::IHDRDecoded)
+        return Error::from_string_literal("IHDR is not the first chunk of the file");
+
     if (chunk_type == "IDAT"sv)
         return process_IDAT(chunk_data, context);
     if (chunk_type == "PLTE"sv)