Add heartbeat extension bounds check.

A missing bounds check in the handling of the TLS heartbeat extension
can be used to reveal up to 64k of memory to a connected client or
server.

Thanks for Neel Mehta of Google Security for discovering this bug and to
Adam Langley <agl@chromium.org> and Bodo Moeller <bmoeller@acm.org> for
preparing the fix (CVE-2014-0160)

(Imported from upstream's 7e840163c06c7692b796a93e3fa85a93136adbb2)
2 files changed