Untrack the connection before closing to avoid possible double-free

From Gangadharan S.A. Fixes issue psycopg#166.
gencer · Jun 20, 2013 · 889b1d8 · 889b1d8
1 parent 9f4b5b3
commit 889b1d8
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diff --git a/NEWS b/NEWS
@@ -5,6 +5,8 @@ What's new in psycopg 2.5.1
   declared (:ticket:`#146`).
 - Fixed comparison of `Range` with non-range objects (:ticket:`#164`).
   Thanks to Chris Withers for the patch.
+- Fixed double-free on connection dealloc (:ticket:`#166`). Thanks to
+  Gangadharan S.A. for the report and fix suggestion.
 
 
 What's new in psycopg 2.5

diff --git a/psycopg/connection_type.c b/psycopg/connection_type.c
@@ -1128,10 +1128,13 @@ connection_dealloc(PyObject* obj)
 {
     connectionObject *self = (connectionObject *)obj;
 
-    conn_close(self);
-
+    /* Make sure to untrack the connection before calling conn_close, which may
+     * allow a different thread to try and dealloc the connection again,
+     * resulting in a double-free segfault (ticket #166). */
     PyObject_GC_UnTrack(self);
 
+    conn_close(self);
+
     if (self->weakreflist) {
         PyObject_ClearWeakRefs(obj);
     }