From: "Robert Święcki" <robert@swiecki.net>
To: Rich Felker <dalias@libc.org>
Cc: GLIBC Devel <libc-alpha@sourceware.org>
Subject: Re: Caching of PID/TID after fork
Date: Thu, 06 Oct 2016 17:42:00 -0000 [thread overview]
Message-ID: <CAP145pjLiwhx4P3XJQCBrpg=OBmaHWyHHOkvT82eSJ4s8aFLZQ@mail.gmail.com> (raw)
In-Reply-To: <20161006172631.GO19318@brightrain.aerifal.cx>
2016-10-06 19:26 GMT+02:00 Rich Felker <dalias@libc.org>:
>> 2. Provide some kind of symbol, which would force for TID/PID to be
>> reloaded in glibc.
>
> There's an easy solution that works with existing versions of glibc
> (and other libcs) with no new symbol or new symbol version dependency:
> call the libc clone() function with a tiny dummy stack and a function
> which does nothing but longjmp out to the caller.
Thanks Rich, that's an interesting idea. I might use it.
Though, IMO, the problem still exist. Some subset of non-trivial
projects which are affected by this behavior:
AFL - https://lcamtuf.blogspot.com/2014/10/fuzzing-binaries-without-execve.html
("because the library caches the result of getpid() when initializing
- and without a way to make it reconsider, PID-dependent calls such as
abort() or raise() will go astray. There is also a library wrapper for
the clone() call that does update the cached PID - but the wrapper is
unwieldy and insists on messing with the process' stack.")
LXC/Docker - https://lists.linuxcontainers.org/pipermail/lxc-devel/2014-August/009920.html
--
Robert Święcki
next prev parent reply other threads:[~2016-10-06 17:42 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-06 16:13 Robert Święcki
2016-10-06 16:34 ` Paul Pluzhnikov
2016-10-06 17:03 ` Robert Święcki
2016-10-06 18:32 ` Adhemerval Zanella
2016-10-06 17:26 ` Rich Felker
2016-10-06 17:42 ` Robert Święcki [this message]
2016-10-06 18:05 ` Rich Felker
2016-10-06 18:26 ` Robert Święcki
2016-10-06 21:35 ` Robert Święcki
2016-10-07 0:42 ` Zack Weinberg
2016-10-07 0:43 ` Zack Weinberg
2016-10-07 14:44 ` Robert Święcki
2016-10-07 18:20 ` Adhemerval Zanella
2016-10-07 18:30 ` Adhemerval Zanella
2016-10-07 19:38 ` Florian Weimer
2016-10-07 21:23 ` Robert Święcki
2016-10-09 10:05 ` Florian Weimer
2016-10-09 14:19 ` Robert Święcki
2016-10-10 18:03 ` Adhemerval Zanella
2016-11-04 15:14 ` Florian Weimer
2016-11-04 16:03 ` Adhemerval Zanella
2016-11-07 16:04 ` Florian Weimer
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