From: Aydın Mercan <aydin@isc.org>
Date: Fri, 6 Feb 2026 12:04:28 +0000 (+0300)
Subject: fix: dev: wipe hmac keys correctly pre-3.0 libcrypto
X-Git-Tag: v9.21.19~38
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3c8c95a50e06d1f5e4c1b3f9cef2dd6d009d1f94;p=thirdparty%2Fbind9.git

fix: dev: wipe hmac keys correctly pre-3.0 libcrypto

A lingering `sizeof` from the prototype era of !11094 caused the
key-wipe in `isc_hmac_key_destroy` to use `sizeof(key->len)` instead of
`key->len` for the length argument of `isc_safe_memwipe`.

This results in a buffer overflow of zero bytes in HMAC keys that are
less than 4 bytes. As such, the overflow can only be visibile in keys
that are less than 32-bits, which is beyond broken and creating such
keys are only possible in testing.

Therefore, this change is *not* a security fix since the conditions are
never reachable in any imaginable deployment scenario.

Builds that use OpenSSL >=3.0 are unaffected as the `sizeof` was only
remaining in pre-3.0 builds.

Closes #5732

Merge branch '5732-invalid-params-to-isc_safe_memwipe' into 'main'

See merge request isc-projects/bind9!11520
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3c8c95a50e06d1f5e4c1b3f9cef2dd6d009d1f94