linux-kernel - Re: flex_array related problems on selinux policy loading

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Message-ID: <1296147449.7567.5780.camel@nimitz>
Date:	Thu, 27 Jan 2011 08:57:29 -0800
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	Steffen Klassert <steffen.klassert@...unet.com>
Cc:	Eric Paris <eparis@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: Re: flex_array related problems on selinux policy loading

On Thu, 2011-01-27 at 13:46 +0100, Steffen Klassert wrote:
> On Wed, Jan 26, 2011 at 08:15:26AM -0800, Dave Hansen wrote:
> > On Wed, 2011-01-26 at 14:04 +0100, Steffen Klassert wrote:
> > > Another thing came to my mind. An atempt to do a zero size allocation
> > > always succeed on kmalloc. If we want to allocate our metadata even in
> > > this case, we should be aware that this allocation _can_ fail. So
> > > flex_array_alloc would not show the same behaviour as kmalloc on zero
> > > size allocations.
> > 
> > I think that's just fine.
> > 
> > You have to check for and handle those allocation failures anyway.  
> 
> If we just return a pointer to the user that notifies that this was a
> zerro size allocation, we would not need to allocate anything (like
> kmalloc does), so we can't get allocation failures.

Could you point me to some of this code?  I'm having a hard time seeing
how this is going to get used, and I don't see any use of
ZERO_SIZE_PTR/ZERO_OR_NULL_PTR() outside of the sl*b code.

-- Dave

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