$NetBSD: patch-CVE-2012-1150-Objects_bufferobject.c,v 1.1 2012/03/25 09:09:05 tron Exp $

Fix for CVE-2012-1150 taken from here:

http://hg.python.org/cpython/rev/6b7704fe1be1

--- Objects/bufferobject.c.orig	2010-05-09 16:15:40.000000000 +0100
+++ Objects/bufferobject.c	2012-03-25 09:51:50.000000000 +0100
@@ -334,10 +334,20 @@
         return -1;
     p = (unsigned char *) ptr;
     len = size;
-    x = *p << 7;
+    /*
+      We make the hash of the empty buffer be 0, rather than using
+      (prefix ^ suffix), since this slightly obfuscates the hash secret
+    */
+    if (len == 0) {
+        self->b_hash = 0;
+        return 0;
+    }
+    x = _Py_HashSecret.prefix;
+    x ^= *p << 7;
     while (--len >= 0)
         x = (1000003*x) ^ *p++;
     x ^= size;
+    x ^= _Py_HashSecret.suffix;
     if (x == -1)
         x = -2;
     self->b_hash = x;