Bug 527400 - Fix OOM null deref from bug 514872, r=jwalden+bmo, a=beltzner

--HG--
extra : rebase_source : 43a222a11bf131b8ef2420ef2d657c84ba452bb3

xpcom/io/nsWildCard.cpp

@@ -422,9 +422,9 @@ ns_WildCardMatch(const T *str, const T *xp, PRBool case_insensitive)
         return _shexp_match(str, xp, case_insensitive, 0);
 
     expr = (T *) NS_Alloc((nsCharTraits<T>::length(xp) + 1) * sizeof(T));
-    memcpy(expr, xp, (nsCharTraits<T>::length(xp) + 1) * sizeof(T));
     if(!expr)
         return NOMATCH;
+    memcpy(expr, xp, (nsCharTraits<T>::length(xp) + 1) * sizeof(T));
 
     x = ::_scan_and_copy(expr, T('~'), T('\0'), static_cast<T*>(NULL));
     if (x != ABORTED && expr[x] == '~') {