linux-kernel - Re: [PATCH] set*uid() must not fail-and-return on OOM/rlimits

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Message-ID: <20060820182137.GO602@1wt.eu>
Date:	Sun, 20 Aug 2006 20:21:38 +0200
From:	Willy Tarreau <w@....eu>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Solar Designer <solar@...nwall.com>,
	Alex Riesen <fork0@...rs.sourceforge.net>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] set*uid() must not fail-and-return on OOM/rlimits

On Sun, Aug 20, 2006 at 07:36:46PM +0100, Alan Cox wrote:
> Ar Sul, 2006-08-20 am 20:10 +0200, ysgrifennodd Willy Tarreau:
> > So I think that while it's bad code in userland, a misunderstood kernel
> > semantic caught the developpers. We can at least make the kernel help them.
> 
> Yeah we could. But unfortunately a competence test with the inability to
> write C code isn't part of the Unix spec.

I know but those programs sometimes ship with distros. How many distros do
not ship with either Xfree86 nor Xorg ?

> You can help them enormously using the gcc extensions so gcc warns about
> any unchecked set*uid call, rather than redesigning expected behaviour
> to cause obscure random kills that won't even be noticed/explained.

Arjan proposed to add a __must_check on the set*uid() function in glibc.
I think that if killing the program is what makes you nervous, we could
at least print a warning in the kernel logs so that the admin of a machine
being abused has a chance to detect what's going on. Would you accept
something like this ?

Willy

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