Why is cld used?

[Andreas Schwab]

Ulrich Drepper <drepper@redhat.com> writes:

|> 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.

In which way is this different from any other ABI violation of the caller?

Andreas.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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