0009-video-readers-png-Refuse-to-handle-multiple-image-he.patch

From e170edd18fcfdd9e6f91ba750fd022cef8d43cd4 Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@axtens.net>
Date: Tue, 6 Jul 2021 14:13:40 +1000
Subject: [PATCH] video/readers/png: Refuse to handle multiple image headers

This causes the bitmap to be leaked. Do not permit multiple image headers.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Upstream: 166a4d61448f74745afe1dac2f2cfb85d04909bf
[Thomas: needed to cherry-pick
e623866d9286410156e8b9d2c82d6253a1b22d08, which fixes CVE-2021-3695]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
---
 grub-core/video/readers/png.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/grub-core/video/readers/png.c b/grub-core/video/readers/png.c
index d715c4629..35ae553c8 100644
--- a/grub-core/video/readers/png.c
+++ b/grub-core/video/readers/png.c
@@ -258,6 +258,9 @@ grub_png_decode_image_header (struct grub_png_data *data)
   int color_bits;
   enum grub_video_blit_format blt;
 
+  if (data->image_width || data->image_height)
+    return grub_error (GRUB_ERR_BAD_FILE_TYPE, "png: two image headers found");
+
   data->image_width = grub_png_get_dword (data);
   data->image_height = grub_png_get_dword (data);
 
-- 
2.41.0