CVS commit: src/lib/libcurses

["matthew green" <mrg%netbsd.org@localhost>]

Module Name:    src
Committed By:   mrg
Date:           Sat May  8 04:29:07 UTC 2021

Modified Files:
        src/lib/libcurses: refresh.c

Log Message:
avoid accessing stack garbage.

on arm64eb resuming vi(1) would often crash.  in makech(), the 'csp'
variable is either set to current window data, or a local stack
variable's address '&blank'.  the window data has many lines of info
stored, and 'csp++' is used per line here.  unfortunately, a case
existed where 'csp++' operated on csp initialised from '&blank' which
eventually crashes when, on my display with 160 columns and 'csp + 155'
exceeds the mapped stack and crashes.

match the '!_cursesi_screen->curwin' conditional that initialises csp,
and avoid csp++ here.  assert() that csp != &blank in both places that
modify csp.

thanks to jdc@ and mlelstv@.

XXX: possibly also should avoid the putch() here as well.


To generate a diff of this commit:
cvs rdiff -u -r1.112 -r1.113 src/lib/libcurses/refresh.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.