[ python-Bugs-1688393 ] sock.recvfrom(-24) crashes

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Bugs item #1688393, was opened at 2007-03-27 00:13
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Andrew Bennetts (spiv)
Assigned to: Nobody/Anonymous (nobody)
Summary: sock.recvfrom(-24) crashes

Initial Comment:
Actually sock.recvfrom(x) crashes or causes memory corruption for all values in -sizeof(PyStringObject) <= x < 0, I think.

This script demonstrates the problem:

import socket, sys
s1 = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s1.bind(('127.0.0.1', 9999))
s2 = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s2.sendto('fdsjkldsfkj', ('127.0.0.1', 9999))
print s1.recvfrom(-24)

Try e.g. -1 instead of -24 as well.

I'm attaching a patch that fixes this bug, and adds a simple test for it too.

Other sock_recv* functions in socketmodule.c seem to already catch negative recvlen values and raise ValueError, but for some reason recvfrom missed out.

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