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    Subject[PATCH 5.12 285/700] crypto: x86/curve25519 - fix cpu feature checking logic in mod_exit
    Date
    From: Hangbin Liu <liuhangbin@gmail.com>

    [ Upstream commit 1b82435d17774f3eaab35dce239d354548aa9da2 ]

    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>
    Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 5af8021b98ce..11b4c83c715e 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);
    }

    --
    2.30.2


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