From: ardi <ardillasdelmonte@gmail.com>
To: musl@lists.openwall.com
Subject: Re: tcmalloc compatibility
Date: Sun, 15 Apr 2018 13:52:10 +0200 [thread overview]
Message-ID: <CA+fZqCVZUUDYQ1YoyDTmw3KpmVDJ3Q+C1363ripfgfhP2ZprGQ@mail.gmail.com> (raw)
In-Reply-To: <20180410211724.GJ4418@port70.net>
On Tue, Apr 10, 2018 at 11:17 PM, Szabolcs Nagy <nsz@port70.net> wrote:
>
> then the wrappers with dlsym(RTLD_NEXT,sym) would not work.
> (malloc checkers, valgrind, sanitizers etc all do it)
I've been using ElectricFence, as my only memory debugger since 1996
or so; mostly with the libc of commercial Unices, but also with glibc
in Linux, and with the OSX libc. I never considered I could run into
the issues commented in this thread, and in fact I never faced these
issues and it always worked as expected (however, I must admit I only
use multithreading for accelerating clearly isolated math-intensive
loops that don't call malloc-related functions from inside the loop).
Said this, when I'm linking with ElectricFence, my brain has the "hack
mode flag" ON (I mean, I always had the feeling that I'm working with
a temporary hack that can fail whenever my link line contains -lefence
, and I'm aware that things can go wrong --I didn't consider thread
safety, but anyway I know ElectricFence can fail if the OS syscalls
that allocate protected memory at buffer ends change their behaviour
in newer versions, or if there's some OS/CPU-dependent subtlety with
alignment, etc...)
I've not tried to use ElectricFence with musl yet... but reading this,
can I suppose it won't work? Is there any "hack mode ON" procedure
(yet easy) that would allow to use ElectricFence (assuming
non-threaded code, which is always my case).
I agree with your commitment to correctness, and I'm not asking for a
safe and guaranteed implementation of function interposition, just
that sometimes I need to break my binaries to make them crash hard as
soon as pointer accesses a byte it shouldn't access.
Cheers,
ardi
next prev parent reply other threads:[~2018-04-15 11:52 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-10 10:22 Denis V. Razumovsky
2018-04-10 14:33 ` Rich Felker
2018-04-10 14:45 ` Bobby Powers
2018-04-10 15:35 ` Rich Felker
[not found] ` <878t9vlzh1.fsf@mid.deneb.enyo.de>
2018-04-10 18:39 ` Rich Felker
2018-04-10 20:33 ` Szabolcs Nagy
2018-04-10 20:44 ` Rich Felker
2018-04-10 21:17 ` Szabolcs Nagy
2018-04-15 11:52 ` ardi [this message]
2018-04-16 4:19 ` Markus Wichmann
2018-04-16 4:40 ` Rich Felker
2018-04-18 20:35 ` Rich Felker
2018-04-19 18:27 ` Szabolcs Nagy
2018-04-19 19:11 ` Rich Felker
2018-04-18 20:50 ` Florian Weimer
2018-04-18 21:06 ` Rich Felker
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