[PATCH] hwrng: pseries - port to new read API and fix stack corruption

[Herbert Xu]

On Fri, Oct 31, 2014 at 07:50:11AM +0100, Greg Kurz wrote:
> The add_early_randomness() function in drivers/char/hw_random/core.c passes
> a 16-byte buffer to pseries_rng_data_read(). Unfortunately, plpar_hcall()
> returns four 64-bit values and trashes 16 bytes on the stack.
> 
> This bug has been lying around for a long time. It got unveiled by:
> 
> commit d3cc7996473a7bdd33256029988ea690754e4e2a
> Author: Amit Shah <amit.shah at redhat.com>
> Date:   Thu Jul 10 15:42:34 2014 +0530
> 
>     hwrng: fetch randomness only after device init
> 
> It may trig a oops while loading or unloading the pseries-rng module for both
> PowerVM and PowerKVM guests.
> 
> This patch does two things:
> - pass an intermediate well sized buffer to plpar_hcall(). This is acceptalbe
>   since we're not on a hot path.
> - move to the new read API so that we know the return buffer size for sure.
> 
> Signed-off-by: Greg Kurz <gkurz at linux.vnet.ibm.com>

Patch applied to crypto.

Thanks,
-- 
Email: Herbert Xu <herbert at gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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