On Thu, Jun 3, 2021 at 7:53 AM Hangbin Liu liuhangbin@gmail.com 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@gmail.com

---

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@vger.kernel.org Reviewed-by: Jason A. Donenfeld Jason@zx2c4.com