From: Adam Stylinski <kungfujesus06@gmail.com>
Date: Fri, 18 Mar 2022 00:22:56 +0000 (-0400)
Subject: Fix a latent issue with chunkmemset
X-Git-Tag: 2.1.0-beta1~326
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e81c083fda107ca37b93304a1fd0aa9e68acfdee;p=thirdparty%2Fzlib-ng.git

Fix a latent issue with chunkmemset

It would seem that on some platforms, namely those which are
!UNALIGNED64_OK, there was a likelihood of chunkmemset_safe_c copying all
the bytes before passing control flow to chunkcopy, a function which is
explicitly unsafe to be called with a zero length copy.

This fixes that bug for those platforms.
---

diff --git a/chunkset_tpl.h b/chunkset_tpl.h
index 189b5ec4..9ea37225 100644
--- a/chunkset_tpl.h
+++ b/chunkset_tpl.h
@@ -171,5 +171,8 @@ Z_INTERNAL uint8_t* CHUNKMEMSET_SAFE(uint8_t *out, unsigned dist, unsigned len,
         }
         return out;
     }
-    return CHUNKMEMSET(out, dist, len);
+    if (len)
+        return CHUNKMEMSET(out, dist, len);
+
+    return out;
 }