Fix invalid memory access in CScript::operator+=

ajtowns · furszy · commit 08c2874bcf2c · 2021-09-09T11:02:08.000-03:00
diff --git a/src/script/script.h b/src/script/script.h
@@ -400,6 +400,7 @@ class CScript : public CScriptBase
 
     CScript& operator+=(const CScript& b)
     {
+        reserve(size() + b.size());
         insert(end(), b.begin(), b.end());
         return *this;
     }
diff --git a/src/test/script_tests.cpp b/src/test/script_tests.cpp
@@ -1172,4 +1172,21 @@ BOOST_AUTO_TEST_CASE(script_FindAndDelete)
     BOOST_CHECK(s == expect);
 }
 
+BOOST_AUTO_TEST_CASE(script_can_append_self)
+{
+    CScript s, d;
+
+    s = ScriptFromHex("00");
+    s += s;
+    d = ScriptFromHex("0000");
+    BOOST_CHECK(s == d);
+
+    // check doubling a script that's large enough to require reallocation
+    static const char hex[] = "04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5f";
+    s = CScript() << ParseHex(hex) << OP_CHECKSIG;
+    d = CScript() << ParseHex(hex) << OP_CHECKSIG << ParseHex(hex) << OP_CHECKSIG;
+    s += s;
+    BOOST_CHECK(s == d);
+}
+
 BOOST_AUTO_TEST_SUITE_END()

Original file line number	Diff line number	Diff line change
`@@ -400,6 +400,7 @@ class CScript : public CScriptBase`
`400`	`400`
`401`	`401`	`CScript& operator+=(const CScript& b)`
`402`	`402`	`{`
	`403`	`+ reserve(size() + b.size());`
`403`	`404`	`insert(end(), b.begin(), b.end());`
`404`	`405`	`return *this;`
`405`	`406`	`}`