src: fix use-after-return in zlib bindings

bnoordhuis · Fishrock123 · commit ce039c324027 · 2016-07-05T22:36:46.000+02:00
Pointed out by Coverity. Introduced in commit 5b8e1da from September 2011 ("Initial pass at zlib bindings".) The asynchronous version of Write() used a pointer to a stack-allocated buffer on flush. A mitigating factor is that zlib does not dereference the pointer for zero-sized writes but it's still technically UB. PR-URL: #7374 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
diff --git a/src/node_zlib.cc b/src/node_zlib.cc
@@ -149,8 +149,7 @@ class ZCtx : public AsyncWrap {
 
     if (args[1]->IsNull()) {
       // just a flush
-      Bytef nada[1] = { 0 };
-      in = nada;
+      in = nullptr;
       in_len = 0;
       in_off = 0;
     } else {
