From: Fabian Keil <fk@fabiankeil.de>
Date: Sat, 6 Feb 2021 10:52:37 +0000 (+0100)
Subject: buf_copy(): Fail if there's no data to write or nothing to do
X-Git-Tag: v_3_0_32~33
X-Git-Url: http://www.privoxy.org/gitweb/?a=commitdiff_plain;h=647353d3e6621b32696a08d66656b7c6bb8fb0a3;p=privoxy.git

buf_copy(): Fail if there's no data to write or nothing to do

Prevents undefined behaviour "applying zero offset to null pointer".

Reported by: Joshua Rogers (Opera)
---

diff --git a/deanimate.c b/deanimate.c
index 494e6a85..b0f3f1f8 100644
--- a/deanimate.c
+++ b/deanimate.c
@@ -131,6 +131,14 @@ static int buf_extend(struct binbuffer *buf, size_t length)
  *********************************************************************/
 static int buf_copy(struct binbuffer *src, struct binbuffer *dst, size_t length)
 {
+   /*
+    * Sanity check: Make sure the source buffer contains
+    * data and there's work to be done.
+    */
+   if (src->buffer == NULL || src->size == 0 || length == 0)
+   {
+      return 1;
+   }
 
    /*
     * Sanity check: Can't copy more data than we have