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crypto: ecdh - avoid unaligned accesses in ecdh_set_secret() 

commit 17858b140b upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Ard Biesheuvel 2020-11-24 11:47:19 +01:00 committed by Greg Kroah-Hartman
parent f26f0e7770
commit 36a58bda87
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;
}