Re: [PATCH] crypto: arm64/aes-neonbs - remove redundant code in __xts_crypt()

[Ard Biesheuvel]

On Tue, 22 Oct 2019 at 08:42, Yunfeng Ye <yeyunfeng@xxxxxxxxxx> wrote:
>
> A warning is found by the static code analysis tool:
>   "Identical condition 'err', second condition is always false"
>
> Fix this by removing the redundant condition @err.
>
> Signed-off-by: Yunfeng Ye <yeyunfeng@xxxxxxxxxx>

Please don't blindly 'fix' crypto code without reading it carefully
and without cc'ing the author.

The correct fix is to add the missing assignment of 'err', like so

diff --git a/arch/arm64/crypto/aes-neonbs-glue.c
b/arch/arm64/crypto/aes-neonbs-glue.c
index ea873b8904c4..e3e27349a9fe 100644
--- a/arch/arm64/crypto/aes-neonbs-glue.c
+++ b/arch/arm64/crypto/aes-neonbs-glue.c
@@ -384,7 +384,7 @@ static int __xts_crypt(struct skcipher_request
*req, bool encrypt,
                        goto xts_tail;

                kernel_neon_end();
-               skcipher_walk_done(&walk, nbytes);
+               err = skcipher_walk_done(&walk, nbytes);
        }

        if (err || likely(!tail))

Does that make the warning go away?


> ---
>  arch/arm64/crypto/aes-neonbs-glue.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/crypto/aes-neonbs-glue.c b/arch/arm64/crypto/aes-neonbs-glue.c
> index ea873b8904c4..7b342db428b0 100644
> --- a/arch/arm64/crypto/aes-neonbs-glue.c
> +++ b/arch/arm64/crypto/aes-neonbs-glue.c
> @@ -387,7 +387,7 @@ static int __xts_crypt(struct skcipher_request *req, bool encrypt,
>                 skcipher_walk_done(&walk, nbytes);
>         }
>
> -       if (err || likely(!tail))
> +       if (likely(!tail))
>                 return err;
>
>         /* handle ciphertext stealing */
> --
> 2.7.4.3
>
>
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