Date: 31 Dec 2003 06:52:19 -0000 From: Colin Percival <cperciva@daemonology.net> To: FreeBSD-gnats-submit@FreeBSD.org Subject: bin/60758: cycle-eating endless loop in lock(1) Message-ID: <20031231065219.3759.qmail@fafnir.daemonology.net> Resent-Message-ID: <200312310700.hBV70aqG061678@freefall.freebsd.org>
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>Number: 60758
>Category: bin
>Synopsis: cycle-eating endless loop in lock(1)
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Tue Dec 30 23:00:35 PST 2003
>Closed-Date:
>Last-Modified:
>Originator: Colin Percival
>Release: FreeBSD 5.2-RC2 i386
>Organization:
>Environment:
System: FreeBSD fafnir.daemonology.net 5.2-RC2 FreeBSD 5.2-RC2 #0: Mon Dec 22 07:23:48 GMT 2003 root@wv1u.freebsd.org:/usr/obj/usr/src/sys/GENERIC i386
>Description:
If fgets(3) fails, lock(1) will enter an endless loop:
write(1,0x804e000,5) ERR#5 'Input/output error'
read(0x0,0x804f000,0x1000) = 0 (0x0)
gettimeofday(0xbfbfe2b0,0x0) = 0 (0x0)
write(1,0x804e000,31) ERR#5 'Input/output error'
[repeat]
>How-To-Repeat:
1. ssh into a machine
2. su
3. lock
4. (with a different terminal) kill the ssh session.
su and lock will continue running, and lock will eat 100% of available cpu
time.
>Fix:
Insert a sleep(1) call into the endless loop. This still leaves an orphan
lying around, but since lock is important for security purposes, this is
probably safer than exiting.
--- lock.diff begins here ---
Index: lock.c
===================================================================
RCS file: /usr/cvs/src/usr.bin/lock/lock.c,v
retrieving revision 1.17
diff -u -r1.17 lock.c
--- lock.c 1 Sep 2003 04:12:18 -0000 1.17
+++ lock.c 31 Dec 2003 06:23:57 -0000
@@ -211,6 +211,7 @@
(void)printf("Key: ");
if (!fgets(s, sizeof(s), stdin)) {
clearerr(stdin);
+ sleep(1);
hi(0);
continue;
}
--- lock.diff ends here ---
>Release-Note:
>Audit-Trail:
>Unformatted:
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