Hi!
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.
Fair enough... but: params.key_size is validated in ecc_is_key_valid(), and that now happens _after_ memcpy.
How is it guaranteed that we don't overflow the buffer during memcpy?
+++ b/crypto/ecdh.c @@ -57,12 +57,13 @@ static int ecdh_set_secret(struct crypto 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;
Best regards, Pavel