libtiff: TIFFReadDirectory(): avoid calling memcpy() with a null source pointer and size of zero (fixes #362) (dd433)

SDL Commits
1

https://github.com/libsdl-org/libtiff/commit/dd433f330b3d1dd90ee476bfef07ed648b2c0975

From dd433f330b3d1dd90ee476bfef07ed648b2c0975 Mon Sep 17 00:00:00 2001
From: Even Rouault <[EMAIL REDACTED]>
Date: Sat, 5 Feb 2022 20:36:41 +0100
Subject: [PATCH] TIFFReadDirectory(): avoid calling memcpy() with a null
 source pointer and size of zero (fixes #362)

Backported from commit 561599c99f987dc32ae110370cfdd7df7975586b
---
 libtiff/tif_dirread.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libtiff/tif_dirread.c b/libtiff/tif_dirread.c
index b6a7d599..6f6b1e25 100644
--- a/libtiff/tif_dirread.c
+++ b/libtiff/tif_dirread.c
@@ -4173,7 +4173,8 @@ TIFFReadDirectory(TIFF* tif)
                     goto bad;
                 }
 
-                memcpy(new_sampleinfo, tif->tif_dir.td_sampleinfo, old_extrasamples * sizeof(uint16));
+                if (old_extrasamples > 0)
+                    memcpy(new_sampleinfo, tif->tif_dir.td_sampleinfo, old_extrasamples * sizeof(uint16));
                 _TIFFsetShortArray(&tif->tif_dir.td_sampleinfo, new_sampleinfo, tif->tif_dir.td_extrasamples);
                 _TIFFfree(new_sampleinfo);
         }