Re: [PATCH] crypto: xts_crypt() return if walk.nbytes is 0

[Ard Biesheuvel]

On Mon, 9 Aug 2021 at 16:10, Shreyansh Chouhan
<chouhan.shreyansh630@xxxxxxxxx> wrote:
>
> xts_crypt() code doesn't call kernel_fpu_end() after calling
> kernel_fpu_begin() if walk.nbytes is 0. The correct behavior should be
> not calling kernel_fpu_begin() if walk.nbytes is 0.
>
> Reported-by: syzbot+20191dc583eff8602d2d@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@xxxxxxxxx>

Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>

> ---
>  arch/x86/crypto/aesni-intel_glue.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
> index 388643ca2177..ec6eac57c493 100644
> --- a/arch/x86/crypto/aesni-intel_glue.c
> +++ b/arch/x86/crypto/aesni-intel_glue.c
> @@ -849,7 +849,7 @@ static int xts_crypt(struct skcipher_request *req, bool encrypt)
>                 return -EINVAL;
>
>         err = skcipher_walk_virt(&walk, req, false);
> -       if (err)
> +       if (err || !walk.nbytes)
>                 return err;
>
>         if (unlikely(tail > 0 && walk.nbytes < walk.total)) {
> --
> 2.31.1
>