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From: Florian Weimer <fweimer@redhat.com>
To: Alejandro Colomar <alx@kernel.org>
Cc: "Arsen Arsenović" <arsen@gentoo.org>, libc-alpha@sourceware.org
Subject: Re: free(3) const void *
Date: Fri, 26 Jan 2024 20:45:50 +0100	[thread overview]
Message-ID: <871qa3280h.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <ZbPRKPSYlvVxaedm@debian> (Alejandro Colomar's message of "Fri, 26 Jan 2024 16:35:04 +0100")

* Alejandro Colomar:

> That would reqire dereferencing the pointer, to actually get the
> lvalue, which free(3) never does.

Just to clarify, our implementation in fact dereferences the pointer,
both to obtain heap metadata (outside the previously allocated object),
and to read from the object itself.  For the latter, see this commit and
subsequent ones:

commit bcdaad21d4635931d1bd3b54a7894276925d081d
Author: DJ Delorie <dj@delorie.com>
Date:   Tue Nov 20 13:24:09 2018 -0500

    malloc: tcache double free check
    
Thanks,
Florian


  parent reply	other threads:[~2024-01-26 19:45 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-26 13:21 Alejandro Colomar
2024-01-26 14:24 ` Arsen Arsenović
2024-01-26 15:35   ` Alejandro Colomar
2024-01-26 17:22     ` Arsen Arsenović
2024-01-26 17:55       ` Xi Ruoyao
2024-01-26 18:11         ` Alejandro Colomar
2024-01-26 20:04           ` Arsen Arsenović
2024-01-26 20:07         ` Arsen Arsenović
2024-01-26 17:40     ` Andreas Schwab
2024-01-26 19:45     ` Florian Weimer [this message]
2024-01-26 15:13 ` Andreas Schwab
2024-01-26 15:33   ` Alejandro Colomar
2024-01-26 18:09 ` Russ Allbery
2024-01-26 18:23   ` Alejandro Colomar
2024-01-26 18:36     ` Xi Ruoyao
2024-01-26 18:40       ` Alejandro Colomar
2024-01-26 18:49         ` Xi Ruoyao
2024-01-26 18:57           ` Alejandro Colomar
2024-01-26 18:40     ` Russ Allbery
2024-01-26 18:45       ` Alejandro Colomar
2024-01-26 19:41   ` Florian Weimer
2024-01-26 18:39 ` [PATCH] Use [[gnu::access(none)]] on free(3) Alejandro Colomar
2024-01-26 18:41   ` Alejandro Colomar
2024-01-26 21:23     ` Paul Eggert
2024-01-26 23:19       ` Alejandro Colomar
2024-01-27 13:21       ` Cristian Rodríguez
2024-02-13 15:19         ` Gabriel Ravier
2024-02-13 15:28           ` Alejandro Colomar
2024-01-26 21:11 ` free(3) const void * DJ Delorie
2024-01-26 21:30   ` Andreas Schwab
2024-01-26 21:47     ` DJ Delorie
2024-01-26 22:07       ` Andreas Schwab
2024-01-26 23:25       ` Alejandro Colomar

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