From: Rich Felker <dalias@libc.org>
To: libc-alpha@sourceware.org
Subject: Re: [PATCH v2 1/3] posix: Remove dynamic memory allocation from execl{e,p}
Date: Tue, 02 Feb 2016 16:33:00 -0000 [thread overview]
Message-ID: <20160202163335.GJ9349@brightrain.aerifal.cx> (raw)
In-Reply-To: <alpine.DEB.2.10.1602011648030.2674@digraph.polyomino.org.uk>
On Mon, Feb 01, 2016 at 04:52:15PM +0000, Joseph Myers wrote:
> On Mon, 1 Feb 2016, Adhemerval Zanella wrote:
>
> > + char *argv[argc+1];
> > + va_start (ap, arg);
> > + argv[0] = (char*) arg;
> > + for (i = 1; i < argc; i++)
> > + argv[i] = va_arg (ap, char *);
> > + argv[i] = NULL;
>
> I don't see how you're ensuring this stack allocation is safe (i.e. if
> it's too big, it doesn't corrupt memory that's in use by other threads).
There's no obligation to. If you pass something like a million
arguments to a variadic function, the compiler will generate code in
the caller that overflows the stack before the callee is even reached.
The size of the vla used in execl is exactly the same size as the
argument block on the stack used for passing arguments to execl from
its caller, and it's nobody's fault but the programmer's if this is
way too big. It's not a runtime variable.
Rich
next prev parent reply other threads:[~2016-02-02 16:33 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-01 16:21 [PATCH 0/3] posix: Execute file function fixes Adhemerval Zanella
2016-02-01 16:21 ` [PATCH v2 1/3] posix: Remove dynamic memory allocation from execl{e,p} Adhemerval Zanella
2016-02-01 16:52 ` Joseph Myers
2016-02-01 17:18 ` Adhemerval Zanella
2016-02-01 17:54 ` Joseph Myers
2016-02-01 18:09 ` Adhemerval Zanella
2016-02-02 11:24 ` Florian Weimer
2016-02-02 12:46 ` Szabolcs Nagy
2016-02-02 12:47 ` Adhemerval Zanella
2016-02-02 16:33 ` Rich Felker [this message]
2016-02-07 21:28 ` Rasmus Villemoes
2016-02-09 11:36 ` Richard Henderson
2016-02-09 13:30 ` Szabolcs Nagy
2016-02-10 16:36 ` Adhemerval Zanella
2016-02-01 16:21 ` [PATCH v4 2/3] posix: execvpe cleanup Adhemerval Zanella
2016-02-01 16:21 ` [PATCH v2 3/3] posix: New Linux posix_spawn{p} implementation Adhemerval Zanella
2016-02-02 13:06 ` Florian Weimer
2016-02-02 13:31 ` Adhemerval Zanella
2016-02-03 11:07 ` Torvald Riegel
2016-02-03 12:05 ` Adhemerval Zanella
2016-02-03 12:06 ` Torvald Riegel
2016-02-03 12:14 ` Adhemerval Zanella
2016-08-31 21:13 ` Rasmus Villemoes
2016-08-31 22:08 ` Joseph Myers
2016-09-01 9:28 ` Rasmus Villemoes
2016-09-14 13:13 ` Adhemerval Zanella
2016-09-14 18:58 ` Rasmus Villemoes
2016-09-14 19:59 ` Adhemerval Zanella
2016-09-20 20:25 ` Florian Weimer
2016-09-20 20:54 ` Rasmus Villemoes
2016-09-20 21:01 ` [PATCH] linux: spawni.c: simplify error reporting to parent Rasmus Villemoes
2016-09-22 20:54 ` Adhemerval Zanella
2016-09-23 5:21 ` Florian Weimer
2016-09-23 19:09 ` Rasmus Villemoes
2016-09-23 19:28 ` Adhemerval Zanella
2016-09-23 20:37 ` Florian Weimer
2016-09-27 20:26 ` Rasmus Villemoes
2016-09-27 21:14 ` Adhemerval Zanella
2016-09-28 14:14 ` Rich Felker
2016-09-28 15:03 ` Andreas Schwab
2016-09-28 15:22 ` Rich Felker
2016-09-28 18:13 ` Adhemerval Zanella
2016-10-06 12:52 ` Florian Weimer
2016-09-06 20:43 ` [PATCH v2 3/3] posix: New Linux posix_spawn{p} implementation Rasmus Villemoes
2016-09-14 19:37 ` Adhemerval Zanella
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