From 9266d14b5ca4e29b970fa03272318e5f99386e06 Mon Sep 17 00:00:00 2001
From: Marcus Meissner <marcus@jet.franken.de>
Date: Thu, 5 Nov 2020 09:50:08 +0100
Subject: [PATCH] fixed a incorrect overflow check that could be optimized
 away.

inspired by:
https://android.googlesource.com/platform/external/libexif/+/8e7345f3bc0bad06ac369d6cbc1124c8ceaf7d4b

https://source.android.com/security/bulletin/2020-11-01

CVE-2020-0452

Downloaded from upstream commit, rebased for 0.6.22:
https://github.com/libexif/libexif/commit/9266d14b5ca4e29b970fa03272318e5f99386e06

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
---
 libexif/exif-entry.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libexif/exif-entry.c b/libexif/exif-entry.c
index 3fc0ff9..4b866ce 100644
--- a/libexif/exif-entry.c
+++ b/libexif/exif-entry.c
@@ -1371,8 +1371,8 @@ exif_entry_get_value (ExifEntry *e, char *val, unsigned int maxlen)
 	{
 		unsigned char *utf16;
 
-		/* Sanity check the size to prevent overflow */
-		if (e->size+sizeof(uint16_t)+1 < e->size) break;
+		/* Sanity check the size to prevent overflow. Note EXIF files are 64kb at most. */
+		if (e->size >= 65536 - sizeof(uint16_t)*2) break;
 
 		/* The tag may not be U+0000-terminated , so make a local
 		   U+0000-terminated copy before converting it */