tree 547072fb16659ed43524d24b15a94fe4c0485c5c
parent 0592ea772aee48ca1e6d9eb84eca8e143033d973
author Hanno Becker <hanno.becker@arm.com> 1539002450 +0100
committer Hanno Becker <hanno.becker@arm.com> 1539002450 +0100

Fix bounds check in ssl_parse_server_psk_hint()

In the previous bounds check `(*p) > end - len`, the computation
of `end - len` might underflow if `end` is within the first 64KB
of the address space (note that the length `len` is controlled by
the peer). In this case, the bounds check will be bypassed, leading
to `*p` exceed the message bounds by up to 64KB when leaving
`ssl_parse_server_psk_hint()`. In a pure PSK-based handshake,
this doesn't seem to have any consequences, as `*p*` is not accessed
afterwards. In a PSK-(EC)DHE handshake, however, `*p` is read from
in `ssl_parse_server_ecdh_params()` and `ssl_parse_server_dh_params()`
which might lead to an application crash of information leakage.