On Thu, Jun 3, 2021 at 7:53 AM Hangbin Liu <liuhangbin@xxxxxxxxx> wrote:
>
> In curve25519_mod_init() the curve25519_alg will be registered only when
> (X86_FEATURE_BMI2 && X86_FEATURE_ADX). But in curve25519_mod_exit()
> it still checks (X86_FEATURE_BMI2 || X86_FEATURE_ADX) when do crypto
> unregister. This will trigger a BUG_ON in crypto_unregister_alg() as
> alg->cra_refcnt is 0 if the cpu only supports one of X86_FEATURE_BMI2
> and X86_FEATURE_ADX.
>
> Fixes: 07b586fe0662 ("crypto: x86/curve25519 - replace with formally verified implementation")
> Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
> ---
> arch/x86/crypto/curve25519-x86_64.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/crypto/curve25519-x86_64.c b/arch/x86/crypto/curve25519-x86_64.c
> index 6706b6cb1d0f..38caf61cd5b7 100644
> --- a/arch/x86/crypto/curve25519-x86_64.c
> +++ b/arch/x86/crypto/curve25519-x86_64.c
> @@ -1500,7 +1500,7 @@ static int __init curve25519_mod_init(void)
> static void __exit curve25519_mod_exit(void)
> {
> if (IS_REACHABLE(CONFIG_CRYPTO_KPP) &&
> - (boot_cpu_has(X86_FEATURE_BMI2) || boot_cpu_has(X86_FEATURE_ADX)))
> + static_branch_likely(&curve25519_use_bmi2_adx))
> crypto_unregister_kpp(&curve25519_alg);
> }
Looks like the error is actually that the `||` should be a `&&`. But
if you'd like to branch on that static key instead, that's fine.
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
