Re: [PATCH 03/15] crypto: arm64/aes - Fix 32-bit aes_mac_update() arg treated as 64-bit

[Ard Biesheuvel]

On Wed, 18 Feb 2026, at 22:34, Eric Biggers wrote:
> Since the 'enc_after' argument to neon_aes_mac_update() and
> ce_aes_mac_update() has type 'int', it needs to be accessed using the
> corresponding 32-bit register, not the 64-bit register.  The upper half
> of the corresponding 64-bit register may contain garbage.
>

How could that happen? Setting the 32-bit alias of a GPR clears the upper half.

> Fixes: 4860620da7e5 ("crypto: arm64/aes - add NEON/Crypto Extensions 
> CBCMAC/CMAC/XCBC driver")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>

Agree with the change but I don't think this needs a cc:stable (or a fixes tag)

> ---
>  arch/arm64/crypto/aes-modes.S | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/crypto/aes-modes.S b/arch/arm64/crypto/aes-modes.S
> index 0e834a2c062c..e793478f37c1 100644
> --- a/arch/arm64/crypto/aes-modes.S
> +++ b/arch/arm64/crypto/aes-modes.S
> @@ -836,11 +836,11 @@ AES_FUNC_START(aes_mac_update)
>  	encrypt_block	v0, w2, x1, x7, w8
>  	eor		v0.16b, v0.16b, v3.16b
>  	encrypt_block	v0, w2, x1, x7, w8
>  	eor		v0.16b, v0.16b, v4.16b
>  	cmp		w3, wzr
> -	csinv		x5, x6, xzr, eq
> +	csinv		w5, w6, wzr, eq
>  	cbz		w5, .Lmacout
>  	encrypt_block	v0, w2, x1, x7, w8
>  	st1		{v0.16b}, [x4]			/* return dg */
>  	cond_yield	.Lmacout, x7, x8
>  	b		.Lmacloop4x
> @@ -850,11 +850,11 @@ AES_FUNC_START(aes_mac_update)
>  	cbz		w3, .Lmacout
>  	ld1		{v1.16b}, [x0], #16		/* get next pt block */
>  	eor		v0.16b, v0.16b, v1.16b		/* ..and xor with dg */
> 
>  	subs		w3, w3, #1
> -	csinv		x5, x6, xzr, eq
> +	csinv		w5, w6, wzr, eq
>  	cbz		w5, .Lmacout
> 
>  .Lmacenc:
>  	encrypt_block	v0, w2, x1, x7, w8
>  	b		.Lmacloop
> -- 
> 2.53.0