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crypto: ecdh - avoid unaligned accesses in ecdh_set_secret()

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ecdh_set_secret() casts a void* pointer to a const u64* in order to
feed it into ecc_is_key_valid(). This is not generally permitted by
the C standard, and leads to actual misalignment faults on ARMv6
cores. In some cases, these are fixed up in software, but this still
leads to performance hits that are entirely avoidable.

So let's copy the key into the ctx buffer first, which we will do
anyway in the common case, and which guarantees correct alignment.

Cc: <stable@vger.kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Ard Biesheuvel 2020-11-24 11:47:19 +01:00 committed by Herbert Xu
parent 05c2a70591
commit 17858b140b
1 changed files with 5 additions and 4 deletions
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9
crypto/ecdh.c
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@ -53,12 +53,13 @@ static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
return ecc_gen_privkey(ctx->curve_id, ctx->ndigits,
ctx->private_key);
if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits,
(const u64 *)params.key, params.key_size) < 0)
return -EINVAL;
memcpy(ctx->private_key, params.key, params.key_size);
if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits,
ctx->private_key, params.key_size) < 0) {
memzero_explicit(ctx->private_key, params.key_size);
return -EINVAL;
}
return 0;
}