https://gitlab.synchro.net/main/sbbs/-/commit/d2cd0a651384b4c6f9ccfd3a
Modified Files:
	src/sbbs3/zmodem.c
Log Message:
Ok, so the real issue Coverity has is the tainting of nX.

Have zmodem_recv_nibble() explicitly range-check all values, and
handle negative values.  If this remains an issue, it can be
untainted with range checks on each nibble, but let's not go there
to start with.
--- SBBSecho 3.23-Linux