py-2.3 socket.inet_pton() segfault.

[gminick]

BPO	781722
Nosy	@loewis

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2003-08-05.06:27:22.000>
created_at = <Date 2003-08-01.20:40:31.000>
labels = ['extension-modules']
title = 'py-2.3 socket.inet_pton() segfault.'
updated_at = <Date 2003-08-05.06:27:22.000>
user = 'https://bugs.python.org/gminick'

bugs.python.org fields:

activity = <Date 2003-08-05.06:27:22.000>
actor = 'loewis'
assignee = 'none'
closed = True
closed_date = None
closer = None
components = ['Extension Modules']
creation = <Date 2003-08-01.20:40:31.000>
creator = 'gminick'
dependencies = []
files = []
hgrepos = []
issue_num = 781722
keywords = []
message_count = 2.0
messages = ['17572', '17573']
nosy_count = 2.0
nosy_names = ['loewis', 'gminick']
pr_nums = []
priority = 'high'
resolution = 'accepted'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue781722'
versions = ['Python 2.3']

[gminick]

It works (read: segfaults) only when compiled without
IPv6 support. Code to exploit this bug:

import socket
socket.inet_pton(socket.AF_INET6, '5aef:2b::8')

It segfaults because of that code from
Modules/socketmodule.c:
---

#ifdef ENABLE_IPV6
   char packed[MAX(sizeof(struct in_addr), sizeof(struct 
in6_addr))];
#else
   char packed[sizeof(struct in_addr)];
#endif
   if (!PyArg_ParseTuple(args, "is:inet_pton", &af, &ip)) {
      return NULL;
   }

   retval = inet_pton(af, ip, packed);

---

Because IPv6 is disabled packet is defined in that way:

char packed[sizeof(struct in_addr)];

but we're still able to ask inet_pton() to convert some
IPv6 address because socket.AF_INET6 constant is
available, but packet buffer is too small to hold IPv6 data.
A simple patch:
#---------------------------------

--- ../../orig/Python-2.3/Modules/socketmodule.c        
Thu Jul 17 18:58:48 2003
+++ socketmodule.c      Fri Aug  1 22:13:30 2003
@@ -2962,6 +2962,14 @@
                return NULL;
        }
 
+#ifndef ENABLE_IPV6
+   if(af == AF_INET6) {
+      PyErr_SetString(socket_error,
+         "can't use AF_INET6, IPv6 is disabled");
+      return NULL;
+   }
+#endif
+
        retval = inet_pton(af, ip, packed);
        if (retval < 0) {
                PyErr_SetFromErrno(socket_error);
#

---

Sorry, if you know about this one already.

[loewis]

Logged In: YES
user_id=21627

Thanks for the patch. Applied as socketmodule.c 1.272 and
1.271.6.1, NEWS 1.831.4.5