tree 3405e6a0fe791a424e27e876a2cf6f8af91ee3d7
parent 94f48e00523ad931f9db4a34b02b92c28298101f
author Hanno Becker <hanno.becker@arm.com> 1567692236 +0100
committer Hanno Becker <hanno.becker@arm.com> 1568018757 +0100

Fixup MD: Avoid always-false pointer comparison

When MBEDTLS_MD_SINGLE_HASH is set, both the underlying digest context
and the HMAC data are embedded into the mbedtls_md_context; otherwise,
they're dynamically allocated and referenced from mbedtls_md_context.

When the HMAC data is embedded in mbedtls_md_context, it's unnecessary
to check whether mbedtls_md_context::hmac_ctx is NULL, because that's
never the case in defined behaviour, but the check has kept for
uniformity so far. However, contrary to the expectation that compilers
would silently remove this check as always false, ARMC6 complains about
it, breaking some tests in all.sh.

This commit fixes this by guarding checks for

   mbedtls_md_context::hmac_ctx == NULL

by !MBEDTLS_MD_SINGLE_HASH.