From f234b8c129c95857b48a9872506114878a0eaf7d Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Fri, 13 Nov 2020 11:49:33 +0100
Subject: [PATCH] LibGfx: Add missing stream error handling in GIF frame
 descriptor parse

If we try to read a sentinel byte but the stream is fresh out of data,
we have to take care of the stream error and bail out right away, or
we'll hit an assertion when exiting the function soon after.

Fixes #3486.
---
 Libraries/LibGfx/GIFLoader.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Libraries/LibGfx/GIFLoader.cpp b/Libraries/LibGfx/GIFLoader.cpp
index 421b7dbe75..6f9272d607 100644
--- a/Libraries/LibGfx/GIFLoader.cpp
+++ b/Libraries/LibGfx/GIFLoader.cpp
@@ -446,6 +446,9 @@ static bool load_gif_frame_descriptors(GIFLoadingContext& context)
         u8 sentinel = 0;
         stream >> sentinel;
 
+        if (stream.handle_any_error())
+            return false;
+
         if (sentinel == 0x21) {
             u8 extension_type = 0;
             stream >> extension_type;