linux-kernel - Re: [PATCH] crypto: x86/aesni - Update aesni_set

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Date: Tue, 12 Mar 2024 08:46:59 +0100
From: Ard Biesheuvel <ardb@...nel.org>
To: "Chang S. Bae" <chang.seok.bae@...el.com>
Cc: linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org, 
	herbert@...dor.apana.org.au, davem@...emloft.net, ebiggers@...nel.org, 
	x86@...nel.org
Subject: Re: [PATCH] crypto: x86/aesni - Update aesni_set_key() to return void

On Mon, 11 Mar 2024 at 22:48, Chang S. Bae <chang.seok.bae@...el.com> wrote:
>
> The aesni_set_key() implementation has no error case, yet its prototype
> specifies to return an error code.
>
> Modify the function prototype to return void and adjust the related code.
>
> Signed-off-by: Chang S. Bae <chang.seok.bae@...el.com>
> Cc: Eric Biggers <ebiggers@...nel.org>
> Cc: linux-crypto@...r.kernel.org
> Cc: x86@...nel.org
> Cc: linux-kernel@...r.kernel.org
> ---
> Previously, Eric identified a similar case in my AES-KL code [1]. Then,
> this parallel issue was realized.
>
> [1]: https://lore.kernel.org/lkml/20230607053558.GC941@sol.localdomain/
> ---
>  arch/x86/crypto/aesni-intel_asm.S  | 5 ++---
>  arch/x86/crypto/aesni-intel_glue.c | 6 +++---
>  2 files changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/crypto/aesni-intel_asm.S b/arch/x86/crypto/aesni-intel_asm.S
> index 411d8c83e88a..7ecb55cae3d6 100644
> --- a/arch/x86/crypto/aesni-intel_asm.S
> +++ b/arch/x86/crypto/aesni-intel_asm.S
> @@ -1820,8 +1820,8 @@ SYM_FUNC_START_LOCAL(_key_expansion_256b)
>  SYM_FUNC_END(_key_expansion_256b)
>
>  /*
> - * int aesni_set_key(struct crypto_aes_ctx *ctx, const u8 *in_key,
> - *                   unsigned int key_len)
> + * void aesni_set_key(struct crypto_aes_ctx *ctx, const u8 *in_key,
> + *                    unsigned int key_len)
>   */
>  SYM_FUNC_START(aesni_set_key)
>         FRAME_BEGIN
> @@ -1926,7 +1926,6 @@ SYM_FUNC_START(aesni_set_key)
>         sub $0x10, UKEYP
>         cmp TKEYP, KEYP
>         jb .Ldec_key_loop
> -       xor AREG, AREG
>  #ifndef __x86_64__
>         popl KEYP
>  #endif
> diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
> index b1d90c25975a..c807b2f48ea3 100644
> --- a/arch/x86/crypto/aesni-intel_glue.c
> +++ b/arch/x86/crypto/aesni-intel_glue.c
> @@ -87,8 +87,8 @@ static inline void *aes_align_addr(void *addr)
>         return PTR_ALIGN(addr, AESNI_ALIGN);
>  }
>
> -asmlinkage int aesni_set_key(struct crypto_aes_ctx *ctx, const u8 *in_key,
> -                            unsigned int key_len);
> +asmlinkage void aesni_set_key(struct crypto_aes_ctx *ctx, const u8 *in_key,
> +                             unsigned int key_len);
>  asmlinkage void aesni_enc(const void *ctx, u8 *out, const u8 *in);
>  asmlinkage void aesni_dec(const void *ctx, u8 *out, const u8 *in);
>  asmlinkage void aesni_ecb_enc(struct crypto_aes_ctx *ctx, u8 *out,
> @@ -241,7 +241,7 @@ static int aes_set_key_common(struct crypto_aes_ctx *ctx,
>                 err = aes_expandkey(ctx, in_key, key_len);
>         else {
>                 kernel_fpu_begin();
> -               err = aesni_set_key(ctx, in_key, key_len);
> +               aesni_set_key(ctx, in_key, key_len);

This will leave 'err' uninitialized.

>                 kernel_fpu_end();
>         }
>
> --
> 2.34.1
>
>