Subject: Re: [PATCH] crypto: vmx - fix copy-paste error in CTR mode

From: Eric Biggers <[email-masked]>
Date: Thu, 14 Mar 2019 19:24:15 -0700

Hi Daniel,

On Fri, Mar 15, 2019 at 01:09:01PM +1100, Daniel Axtens wrote:
> The original assembly imported from OpenSSL has two copy-paste
> errors in handling CTR mode. When dealing with a 2 or 3 block tail,
> the code branches to the CBC decryption exit path, rather than to
> the CTR exit path.

So does this need to be fixed in OpenSSL too?

> 
> This leads to corruption of the IV, which leads to subsequent blocks
> being corrupted.
> 
> This can be detected with libkcapi test suite, which is available at
> https://github.com/smuellerDD/libkcapi
> 

Is this also detected by the kernel's crypto self-tests, and if not why not?
What about with the new option CONFIG_CRYPTO_MANAGER_EXTRA_TESTS=y?

> Reported-by: Ondrej Mosnáček <[email-masked]>
> Fixes: 5c380d623ed3 ("crypto: vmx - Add support for VMS instructions by ASM")
> Cc: [email-masked]
> Signed-off-by: Daniel Axtens <[email-masked]>
> ---
>  drivers/crypto/vmx/aesp8-ppc.pl | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/crypto/vmx/aesp8-ppc.pl b/drivers/crypto/vmx/aesp8-ppc.pl
> index d6a9f63d65ba..de78282b8f44 100644
> --- a/drivers/crypto/vmx/aesp8-ppc.pl
> +++ b/drivers/crypto/vmx/aesp8-ppc.pl
> @@ -1854,7 +1854,7 @@ Lctr32_enc8x_three:
>  	stvx_u		$out1,$x10,$out
>  	stvx_u		$out2,$x20,$out
>  	addi		$out,$out,0x30
> -	b		Lcbc_dec8x_done
> +	b		Lctr32_enc8x_done
>  
>  .align	5
>  Lctr32_enc8x_two:
> @@ -1866,7 +1866,7 @@ Lctr32_enc8x_two:
>  	stvx_u		$out0,$x00,$out
>  	stvx_u		$out1,$x10,$out
>  	addi		$out,$out,0x20
> -	b		Lcbc_dec8x_done
> +	b		Lctr32_enc8x_done
>  
>  .align	5
>  Lctr32_enc8x_one:
> -- 
> 2.19.1
>