CVE-2024-42098

In the Linux kernel, the following vulnerability has been resolved:

crypto: ecdh - explicitly zeroize private_key

privatekey 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 privatekey array first.

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