Date: Wed, 22 Mar 2000 00:40:13 +0100 (CET) From: Edwin.Groothuis@cgmd76206.chello.nl (mavetju@chello.nl) To: FreeBSD-gnats-submit@freebsd.org Subject: kern/17539: kernel panic when asking help in visual userconfig Message-ID: <200003212340.AAA00567@cgmd76206.chello.nl>
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>Number: 17539
>Category: kern
>Synopsis: kernel panic when asking help in visual userconfig
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Tue Mar 21 15:50:01 PST 2000
>Closed-Date:
>Last-Modified:
>Originator: Edwin Groothuis
>Release: FreeBSD 3.4-RELEASE i386
>Organization:
-
>Environment:
visual config help
>Description:
When in the visual user configuration and I ask for help
and press space several times to get aa the bottom, at the
last time space is entered the kernel will stop with a
kernel-panic.
This is a fix to kern/14394
>How-To-Repeat:
Reset your computer.
Enter "boot user_config"
Enter "visual"
Enter "?" for help
Press space a couple of times
Computer will hang with a kernel panic
>Fix:
The problem is when you are at the end of the help (i.e.
helptext[line]=NULL) and getchar() is being called. At that
moment delta=0. If you press space for the next page, the
delta nor topline are changed because helptext[line]==NULL.
Back at the top of the for(;;)-loop, delta is stil 0 (was
not changed), line is set to 0, the if (delta) failes (so
line is still 0), getchar() is ran, space is pressed,
helptext[line] is checked and found valid, topline is
increased, delta is set and back the helptext is displayed
again with an invalid value of topline for helptext.
In /sys/i386/i386/userconfig.c:
static void
helpscreen(void)
{
int topline = 0; /* where we are in the text */
int c, delta = 1;
char prompt[80];
+ int line = 0;
for (;;) /* loop until user quits */
{
- int line = 0;
/* display help text */
if (delta)
{
clear(); /* remove everything else */
for (line = topline;
(line < (topline + 24)) && (helptext[line]);
Perhaps there is a more elegant solution with working with
topline instead of line at the checking for space, but this
one works.
>Release-Note:
>Audit-Trail:
>Unformatted:
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