linux-kernel - Re: [PATCH] s390/crypto: fix scatterwalk

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Message-ID: <YoPi5eH+oFJ2anQh@osiris>
Date:   Tue, 17 May 2022 20:01:09 +0200
From:   Heiko Carstens <hca@...ux.ibm.com>
To:     Jann Horn <jannh@...gle.com>,
        Harald Freudenberger <freude@...ux.ibm.com>
Cc:     Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        linux-crypto@...r.kernel.org,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] s390/crypto: fix scatterwalk_unmap() callers in AES-GCM

On Tue, May 17, 2022 at 04:30:47PM +0200, Jann Horn wrote:
> The argument of scatterwalk_unmap() is supposed to be the void* that was
> returned by the previous scatterwalk_map() call.
> The s390 AES-GCM implementation was instead passing the pointer to the
> struct scatter_walk.
> 
> This doesn't actually break anything because scatterwalk_unmap() only uses
> its argument under CONFIG_HIGHMEM and ARCH_HAS_FLUSH_ON_KUNMAP.
> 
> Note that I have not tested this patch in any way, not even compile-tested
> it.
> 
> Fixes: bf7fa038707c ("s390/crypto: add s390 platform specific aes gcm support.")
> Signed-off-by: Jann Horn <jannh@...gle.com>
> ---
> IDK which tree this has to go through - s390 or crypto?
> maybe s390 is better, since they can actually test it?
> 
>  arch/s390/crypto/aes_s390.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

This can go via the s390 tree, however I'd like to have an ACK from
Harald, who wrote the original code.

> diff --git a/arch/s390/crypto/aes_s390.c b/arch/s390/crypto/aes_s390.c
> index 54c7536f2482..1023e9d43d44 100644
> --- a/arch/s390/crypto/aes_s390.c
> +++ b/arch/s390/crypto/aes_s390.c
> @@ -701,7 +701,7 @@ static inline void _gcm_sg_unmap_and_advance(struct gcm_sg_walk *gw,
>  					     unsigned int nbytes)
>  {
>  	gw->walk_bytes_remain -= nbytes;
> -	scatterwalk_unmap(&gw->walk);
> +	scatterwalk_unmap(gw->walk_ptr);
>  	scatterwalk_advance(&gw->walk, nbytes);
>  	scatterwalk_done(&gw->walk, 0, gw->walk_bytes_remain);
>  	gw->walk_ptr = NULL;
> @@ -776,7 +776,7 @@ static int gcm_out_walk_go(struct gcm_sg_walk *gw, unsigned int minbytesneeded)
>  		goto out;
>  	}
>  
> -	scatterwalk_unmap(&gw->walk);
> +	scatterwalk_unmap(gw->walk_ptr);
>  	gw->walk_ptr = NULL;
>  
>  	gw->ptr = gw->buf;
> 
> base-commit: 42226c989789d8da4af1de0c31070c96726d990c
> -- 
> 2.36.0.550.gb090851708-goog
>