linux-kernel - Re: 3.6rc6 slab corruption.

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Message-ID: <20120918203713.GB19300@phenom.dumpdata.com>
Date:	Tue, 18 Sep 2012 16:37:13 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Suzuki Poulose <suzuki@...ibm.com>,
	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
Subject: Re: 3.6rc6 slab corruption.

> >> It should be easyish to fix by just adding a lock around those things.
> >
> > Like this:
> 
> Not quite.

.. new patch in another email...
.. snip..
> > Yikes. The fix could be to allocate a buffer large enough for the maximum
> > that %u could take * array_size and not bother with the first pass.
> 
> That's the simple approach. An alternative approach would be to start
> with a reasonable guess as to the size, and use krealloc() if needed
> to expand.
> 
> What are the realistic array sizes? If we're talking about arrays of
> just 16 words or something, just do the maximum (what, 12 bytes per
> 32-bit word? 11 bytes for the number, and then space/NUL after that).

30 words. ~360 + 29 spaces + NULL = 390?
> 
> If we're talking about potentially much bigger arrays, maybe we need
> to use krealloc() to handle it without wasting tons of memory for the
> common case..
> 
>              Linus
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