From e1ee7d9aa1936d5d2f8c7e1a453ad669ed6b38dd Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Thu, 17 Feb 2022 15:28:43 +0100
Subject: [PATCH] (CVE-2022-0908) TIFFFetchNormalTag(): avoid calling memcpy()
 with a null source pointer and size of zero (fixes #383)

(cherry picked from commit a95b799f65064e4ba2e2dfc206808f86faf93e85)
---
 libtiff/tif_dirread.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libtiff/tif_dirread.c b/libtiff/tif_dirread.c
index d68aecc5..b72e6a3b 100644
--- a/libtiff/tif_dirread.c
+++ b/libtiff/tif_dirread.c
@@ -4972,7 +4972,10 @@ TIFFFetchNormalTag(TIFF* tif, TIFFDirEntry* dp, int recover)
 								_TIFFfree(data);
 							return(0);
 						}
-						_TIFFmemcpy(o,data,(uint32)dp->tdir_count);
+						if (dp->tdir_count > 0 )
+						{
+							_TIFFmemcpy(o,data,(uint32)dp->tdir_count);
+						}
 						o[(uint32)dp->tdir_count]=0;
 						if (data!=0)
 							_TIFFfree(data);