c2i_ASN1_BIT_STRING takes length as a long but uses it as an int. Check bounds
before doing so. Previously, excessively large inputs to the function could
write a single byte outside the target buffer. (This is unreachable as
asn1_ex_c2i already uses int for the length.)
Thanks to NCC for finding this issue.
Change-Id: I7ae42214ca620d4159fa01c942153717a7647c65
Reviewed-on: https://boringssl-review.googlesource.com/19204
Reviewed-by: Martin Kreichgauer <martinkr@google.com>
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
3c995f30e7