Removes a case in mbedtls_asn1_named_data() where memcpy() could be
called with a null pointer and zero length. A test case is added for
this code path, to catch the undefined behavior when running tests with
UBSan.
Signed-off-by: Werner Lewis <werner.lewis@arm.com>
Use the test-many-sizes framework for string writes as
well (previously, it was only used for booleans and integers). This
way, more edge cases are tested with less test code.
This commit removes buffer overwrite checks. Instead of these checks,
run the test suite under a memory sanitizer (which we do in our CI).
Omit negative integers and MPIs that would result in values that look
like negative INTEGERs, since the library doesn't respect the
specifications there, but fixing it has a serious risk of breaking
interoperability when ASN.1 is used in X.509 and other
cryptography-related applications.
