tree e38ee79f678aa1034666fc058e3ae20a30ae36b8
parent 49bd3e897e4ff7dfc1c09351213b3e22470abc7e
author k-stachowiak <krzysiek.stachowiak@gmail.com> 1560159978 +0200
committer k-stachowiak <krzysiek.stachowiak@gmail.com> 1560159978 +0200

Add a test for signing content with a long ECDSA key

Due to the way the current PK API works, it may have not been clear
for the library clients, how big output buffers they should pass
to the signing functions. Depending on the key type they depend on
MPI or EC specific compile-time constants.

Inside the library, there were places, where it was assumed that
the MPI size will always be enough, even for ECDSA signatures.
However, for very small sizes of the MBEDTLS_MPI_MAX_SIZE and
sufficiently large key, the EC signature could exceed the MPI size
and cause a stack overflow.

This test establishes both conditions -- small MPI size and the use
of a long ECDSA key -- and attempts to sign an arbitrary file.
This can cause a stack overvlow if the signature buffers are not
big enough, therefore the test is performed for an ASan build.