From 051ae7c282b5487a0dfb5214b9855cd45066c813 Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Mon, 16 May 2022 11:07:26 -0400
Subject: Improve handling of replacing stream data with empty strings

When an empty string was passed to replaceStreamData, the code was
passing a null pointer to memcpy. Since a 0 size was also passed, this
was harmless, but it triggers sanitizer errors. The code properly
handles a null pointer as the buffer in other places.
---
 libqpdf/QPDFObjectHandle.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

(limited to 'libqpdf/QPDFObjectHandle.cc')

diff --git a/libqpdf/QPDFObjectHandle.cc b/libqpdf/QPDFObjectHandle.cc
index 10fb153c..4a61f595 100644
--- a/libqpdf/QPDFObjectHandle.cc
+++ b/libqpdf/QPDFObjectHandle.cc
@@ -1468,7 +1468,9 @@ QPDFObjectHandle::replaceStreamData(
     assertStream();
     auto b = std::make_shared<Buffer>(data.length());
     unsigned char* bp = b->getBuffer();
-    memcpy(bp, data.c_str(), data.length());
+    if (bp) {
+        memcpy(bp, data.c_str(), data.length());
+    }
     dynamic_cast<QPDF_Stream*>(obj.get())->replaceStreamData(
         b, filter, decode_parms);
 }
-- 
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