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crypto: ecdh - explicitly zeroize private_key

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private_key is overwritten with the key parameter passed in by the
caller (if present), or alternatively a newly generated private key.
However, it is possible that the caller provides a key (or the newly
generated key) which is shorter than the previous key. In that
scenario, some key material from the previous key would not be
overwritten. The easiest solution is to explicitly zeroize the entire
private_key array first.

Note that this patch slightly changes the behavior of this function:
previously, if the ecc_gen_privkey failed, the old private_key would
remain. Now, the private_key is always zeroized. This behavior is
consistent with the case where params.key is set and ecc_is_key_valid
fails.

Signed-off-by: Joachim Vandersmissen <git@jvdsn.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Joachim Vandersmissen 2024-03-28 11:24:30 -05:00 committed by Herbert Xu
parent 5adf213cf2
commit 73e5984e54
1 changed files with 2 additions and 0 deletions
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2
crypto/ecdh.c
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@ -33,6 +33,8 @@ static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
params.key_size > sizeof(u64) * ctx->ndigits)
return -EINVAL;
memset(ctx->private_key, 0, sizeof(ctx->private_key));
if (!params.key || !params.key_size)
return ecc_gen_privkey(ctx->curve_id, ctx->ndigits,
ctx->private_key);