linux-kernel - Re: capget() overflows buffers.

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Message-ID: <20080524081754.GW30402@sequoia.sous-sol.org>
Date:	Sat, 24 May 2008 01:17:54 -0700
From:	Chris Wright <chrisw@...s-sol.org>
To:	"Andrew G. Morgan" <morgan@...nel.org>
Cc:	Chris Wright <chrisw@...s-sol.org>,
	Dave Jones <davej@...emonkey.org.uk>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	bojan@...ursive.com, "Serge E. Hallyn" <serue@...ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Security Modules List 
	<linux-security-module@...r.kernel.org>
Subject: Re: capget() overflows buffers.

* Andrew G. Morgan (morgan@...nel.org) wrote:
> Chris Wright wrote:
> | Hmm, it would be kind of nice to have a formalized way get the size,
> | perhaps it would help with KaiGai's request for caps printed out.
> | Something that tells us either the number of u32s, or the max bit
> | supported?
>
> Serge has already provided one  with the call,
>
> ~   sys_prctl(PR_CAPBSET_READ, x);
>
> returns -EINVAL if (x > max-supported-capability).
>
> (Ref: 3b7391de67da515c91f48aa371de77cb6cc5c07e)

Yeah, that's a little roundabout..

> Just to be clear, you are not referring to a warning that the
> application is stuck in a 32-bit capability world, because we already
> have one of those: warn_legacy_capability_use(). You are referring to a
> warning that might indicate a problem with code like that given in your
> example - in which case I'll respond to that part of the thread...

Yes, like the one in the patch I sent that added a
warn_broken_capability_use().

thanks,
-chris
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