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
---
NEWS | 3 ++-
libexif/exif-entry.c | 4 ++--
2 files changed, 4 insertions(+), 3 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 */