tree 07950512dbca4c48369966153f112b8298bad88d
parent b807c2fbab2128cf3746bb2ebd51cbe3bb6914a9
author Benjamin Kaduk <bkaduk@akamai.com> 1651513257 -0700
committer Benjamin Kaduk <kaduk@mit.edu> 1652078914 -0700

evp_md: assert digest is provided for algctx reuse

When reusing an algctx (it was always freed on reinitialization,
prior to #18105), assert that the associated digest is provided.
We implicitly rely on this for algctx reuse to be safe (since
an implicit fetch could potentially change the digest object used,
including provider, which accordingly could change the layout of the
algctx object.

From code inspection, this is currently always the case -- the only
way to set an algctx requires the provider to be set, and the only
ways to change or remove a provider without destroying the entier
EVP_MD_CTX will also free the algctx.  Adding an assertion will help
ensure that this remains true as the code evolves.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18224)