Copied from Debian

From 1f7359b00663804d96c3a102bcb6ead9812c1509 Mon Sep 17 00:00:00 2001
From: erouault <erouault>
Date: Tue, 23 Dec 2014 10:15:35 +0000
Subject: [PATCH] * libtiff/tif_read.c: fix several invalid comparisons of a
 uint64 value with <= 0 by casting it to int64 first. This solves crashing bug
 on corrupted images generated by afl.

---
 ChangeLog          | 6 ++++++
 libtiff/tif_read.c | 6 +++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/libtiff/tif_read.c b/libtiff/tif_read.c
index 2ba822a..dfc5b07 100644
--- a/libtiff/tif_read.c
+++ b/libtiff/tif_read.c
@@ -458,7 +458,7 @@ TIFFReadRawStrip(TIFF* tif, uint32 strip, void* buf, tmsize_t size)
 		return ((tmsize_t)(-1));
 	}
 	bytecount = td->td_stripbytecount[strip];
-	if (bytecount <= 0) {
+	if ((int64)bytecount <= 0) {
 #if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
 		TIFFErrorExt(tif->tif_clientdata, module,
 			     "%I64u: Invalid strip byte count, strip %lu",
@@ -498,7 +498,7 @@ TIFFFillStrip(TIFF* tif, uint32 strip)
 	if ((tif->tif_flags&TIFF_NOREADRAW)==0)
 	{
 		uint64 bytecount = td->td_stripbytecount[strip];
-		if (bytecount <= 0) {
+		if ((int64)bytecount <= 0) {
 #if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
 			TIFFErrorExt(tif->tif_clientdata, module,
 				"Invalid strip byte count %I64u, strip %lu",
@@ -801,7 +801,7 @@ TIFFFillTile(TIFF* tif, uint32 tile)
 	if ((tif->tif_flags&TIFF_NOREADRAW)==0)
 	{
 		uint64 bytecount = td->td_stripbytecount[tile];
-		if (bytecount <= 0) {
+		if ((int64)bytecount <= 0) {
 #if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
 			TIFFErrorExt(tif->tif_clientdata, module,
 				"%I64u: Invalid tile byte count, tile %lu",
