From: David Daney <ddaney.cavm@gmail.com>
To: "Kasatkin, Dmitry" <dmitry.kasatkin@intel.com>
Cc: herbert@gondor.hengli.com.au,
linux-crypto <linux-crypto@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-security-module <linux-security-module@vger.kernel.org>
Subject: Re: on stack dynamic allocations
Date: Thu, 16 Aug 2012 14:30:57 -0700 [thread overview]
Message-ID: <502D6691.5010101@gmail.com> (raw)
In-Reply-To: <CALLzPKYzc5FwPFTn5Ztg58vfkMO2EZ8P-MLEmVXRqdBE+CkkSg@mail.gmail.com>
On 08/16/2012 02:20 PM, Kasatkin, Dmitry wrote:
> Hello,
>
> Some places in the code uses variable-size allocation on stack..
> For example from hmac_setkey():
>
> struct {
> struct shash_desc shash;
> char ctx[crypto_shash_descsize(hash)];
> } desc;
>
>
> sparse complains
>
> CHECK crypto/hmac.c
> crypto/hmac.c:57:47: error: bad constant expression
>
> I like it instead of kmalloc..
>
> But what is position of kernel community about it?
If you know that the range of crypto_shash_descsize(hash) is bounded,
just use the upper bound.
If the range of crypto_shash_descsize(hash) is unbounded, then the stack
will overflow and ... BOOM!
David Daney
next prev parent reply other threads:[~2012-08-16 21:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-16 21:20 on stack dynamic allocations Kasatkin, Dmitry
2012-08-16 21:30 ` David Daney [this message]
2012-08-17 8:18 ` Jussi Kivilinna
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