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Re: Why is cld used?
- From: Ulrich Drepper <drepper at redhat dot com>
- To: "H. J. Lu" <hjl at lucon dot org>
- Cc: GNU C Library <libc-alpha at sources dot redhat dot com>
- Date: Mon, 30 Jun 2003 18:05:54 -0700
- Subject: Re: Why is cld used?
- Organization: Red Hat, Inc.
- References: <20030701004150.GA32230@lucon.org>
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H. J. Lu wrote:
> According to the i386 psABI, the direct flag should be set to zero
> before entry and upon exit from a function, why does glibc use
> "cld" in some functions where the direct flag won't be changed?
And what happens if some incorrect code (or some attacker) adds std and
leaves it this way before jumping into libc? Nice way to open security
holes. The clds are necessary.
- --
- --------------. ,-. 444 Castro Street
Ulrich Drepper \ ,-----------------' \ Mountain View, CA 94041 USA
Red Hat `--' drepper at redhat.com `---------------------------
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