Re: Joy of this, Joy of that

Lawrence D'Oliveiro <ldo@nz.invalid> writes:

On Mon, 25 Nov 2024 08:57:09 +0000, Richard Kettlewell wrote:

Lawrence D'Oliveiro <ldo@nz.invalid> writes:

Richard Kettlewell wrote:

Lawrence D'Oliveiro <ldo@nz.invalid> writes:
>

and that particular case is easy to catch anyway, and glibc does so
by default. See <https://manpages.debian.org/3/mallopt.3.en.html>.

 
Glibc’s double free detection is heuristic, not 100% reliable.

 
(It’s documented as heuristic in the Glibc internals documentation and a
glance at the implementation does seem to agree with that.)
 

If that were true, the examples on the man page wouldn’t work.

 
No, that doesn’t follow. “Not 100% reliable” doesn’t mean specific
examples don’t work.

>
Why not? The examples show that freeing the same pointer twice can be
detected reliably.

They do no such thing. They show that one very simple usage pattern is
detected. They tell you nothing about the ability to detect double frees
in a more complex system.

--
https://www.greenend.org.uk/rjk/