full-disclosure - Re: Python 2.5 (Modules/zlib) minigzip local buffer overflow vulnerability

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Date: Thu, 15 Mar 2007 23:00:23 +0100
From: Ulf Harnhammar <metaur@...ia.com>
To: full-disclosure@...ts.grok.org.uk
Subject: Re: Python 2.5 (Modules/zlib) minigzip local
	buffer overflow vulnerability

> Using strncpy is just strcpy + strlen
> anyway it can't have a big speed impact or anything.

That's not really true. If you check the Linux manpage for strncpy(3),
it says:

       char *strncpy(char *dest, const char *src, size_t n);
[blah]
       In the case where the length of src is less than that of n, the remain-
       der of dest will be padded with null bytes.

"The C Programming Language" agrees:

"Pad with '\0's if t has fewer than n characters."

Thus, replacing strcpy(3) calls with strncpy(3) can have definite 
impacts on performance.

Regards, Ulf Harnhammar

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