Date: Fri, 15 May 1998 16:38:01 -0400 (EDT) From: Max Euston <meuston@jmrodgers.com> To: FreeBSD-gnats-submit@FreeBSD.ORG Subject: bin/6648: [Patch] Can get NULL pointer in vidattr (ncurses) Message-ID: <199805152038.QAA13142@gw.jmrodgers.com>
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>Number: 6648
>Category: bin
>Synopsis: [Patch] Can get NULL pointer in vidattr (ncurses)
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Fri May 15 13:40:01 PDT 1998
>Last-Modified:
>Originator: Max Euston
>Organization:
>Release: FreeBSD 2.2.5-STABLE i386
>Environment:
-STABLE (and -CURRENT) (since revision 1.3)
>Description:
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').
>How-To-Repeat:
main()
{
setupterm(...);
vidputs(...); /* This will SIGSEGV */
}
>Fix:
diff -u /usr/src/lib/libncurses/lib_vidattr.c ./lib_vidattr.c
--- /usr/src/lib/libncurses/lib_vidattr.c Tue Sep 2 15:10:19 1997
+++ ./lib_vidattr.c Fri May 15 14:16:42 1998
@@ -71,13 +71,14 @@
}
}
-#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 @@
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 @@
}
previous_attr = newmode;
+ if (SP)
+ SP->_current_attr = previous_attr;
T(("vidputs finished"));
return OK;
>Audit-Trail:
>Unformatted:
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