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SubjectRe: [PATCH 2/3] crypto: ccp - return an actual key size from RSA max_size callback
On Sat, Feb 24, 2018 at 05:03:21PM +0100, Maciej S. Szmigiero wrote:
> rsa-pkcs1pad uses a value returned from a RSA implementation max_size
> callback as a size of an input buffer passed to the RSA implementation for
> encrypt and sign operations.
> CCP RSA implementation uses a hardware input buffer which size depends only
> on the current RSA key length, so it should return this key length in
> the max_size callback, too.
> This also matches what the kernel software RSA implementation does.
> Previously, the value returned from this callback was always the maximum
> RSA key size the CCP hardware supports.
> This resulted in this huge buffer being passed by rsa-pkcs1pad to CCP even
> for smaller key sizes and then in a buffer overflow when ccp_run_rsa_cmd()
> tried to copy this large input buffer into a RSA key length-sized hardware
> input buffer.
> Signed-off-by: Maciej S. Szmigiero <>
> Fixes: ceeec0afd684 ("crypto: ccp - Add support for RSA on the CCP")
> Cc:

Patch applied. Thanks.
Email: Herbert Xu <>
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