Low level use of 'vidattr()' can cause a NULL pointer to be

dereferenced.  This is because 'SP' is only initialized via 'newterm()'
(which is not required if you are going to interact with the 'terminfo'
database without using 'ncurses').

PR: 6648
Submitted by: Max Euston <meuston@jmrodgers.com>

1 files changed, 11 insertions, 5 deletions

diff --git a/lib/libncurses/lib_vidattr.c b/lib/libncurses/lib_vidattr.c
index 0bb5675..ef82139 100644
--- a/lib/libncurses/lib_vidattr.c
+++ b/lib/libncurses/lib_vidattr.c
@@ -71,13 +71,14 @@ int fg, bg;
 	}
 }
 
-#define previous_attr SP->_current_attr
-
 int vidputs(chtype newmode, int  (*outc)(int))
 {
-chtype	turn_off = (~newmode & previous_attr) & ~A_COLOR;
-chtype	turn_on  = (newmode & ~previous_attr) & ~A_COLOR;
-int pair, current_pair;
+static chtype  previous_attr=0;
+chtype	turn_off,turn_on;
+int	pair, current_pair;
+
+	if (SP)
+		previous_attr = SP->_current_attr;
 
 	T(("vidputs(%x) called %s", newmode, _traceattr(newmode)));
 	T(("previous attribute was %s", _traceattr(previous_attr)));
@@ -85,6 +86,9 @@ int pair, current_pair;
 	if (newmode == previous_attr)
 		return OK;
 
+	turn_off = (~newmode & previous_attr) & ~A_COLOR;
+	turn_on  = (newmode & ~previous_attr) & ~A_COLOR;
+
 	pair = PAIR_NUMBER(newmode);
 	current_pair = PAIR_NUMBER(previous_attr);
 
@@ -184,6 +188,8 @@ int pair, current_pair;
    	}
 
 	previous_attr = newmode;
+	if (SP)
+		SP->_current_attr = previous_attr;
 
 	T(("vidputs finished"));
 	return OK;