Module Name: src
Committed By: ad
Date: Mon Jan 6 11:18:51 UTC 2020
Modified Files:
src/sys/kern: tty.c
Log Message:
ttygetinfo(): avoid crash with zombies. From skrll@, tweaked by me.
To generate a diff of this commit:
cvs rdiff -u -r1.283 -r1.284 src/sys/kern/tty.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/tty.c
diff -u src/sys/kern/tty.c:1.283 src/sys/kern/tty.c:1.284
--- src/sys/kern/tty.c:1.283 Thu Jan 2 16:52:55 2020
+++ src/sys/kern/tty.c Mon Jan 6 11:18:51 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: tty.c,v 1.283 2020/01/02 16:52:55 skrll Exp $ */
+/* $NetBSD: tty.c,v 1.284 2020/01/06 11:18:51 ad Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -63,7 +63,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tty.c,v 1.283 2020/01/02 16:52:55 skrll Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tty.c,v 1.284 2020/01/06 11:18:51 ad Exp $");
#ifdef _KERNEL_OPT
#include "opt_compat_netbsd.h"
@@ -2533,11 +2533,13 @@ ttygetinfo(struct tty *tp, int fromsig,
const char *msg;
char lmsg[100];
long rss;
+ bool again = false;
KASSERT(mutex_owned(proc_lock));
*buf = '\0';
+ retry:
if (tp->t_session == NULL)
msg = "not a controlling terminal\n";
else if (tp->t_pgrp == NULL)
@@ -2568,11 +2570,26 @@ ttygetinfo(struct tty *tp, int fromsig,
if (p->p_lock != oldpick->p_lock)
mutex_exit(oldpick->p_lock);
}
- if (fromsig &&
- (SIGACTION_PS(pick->p_sigacts, SIGINFO).sa_flags &
- SA_NOKERNINFO))
- return;
- msg = NULL;
+
+ if (pick != NULL) {
+ mutex_enter(pick->p_lock);
+ if (P_ZOMBIE(pick)) {
+ mutex_exit(pick->p_lock);
+ pick = NULL;
+ if (!again) {
+ again = true;
+ goto retry;
+ }
+ msg = "found only zombie processes\n";
+ }
+ if (fromsig &&
+ (SIGACTION_PS(pick->p_sigacts, SIGINFO).sa_flags &
+ SA_NOKERNINFO)) {
+ mutex_exit(pick->p_lock);
+ return;
+ }
+ msg = NULL;
+ }
}
/* Print load average. */
@@ -2589,7 +2606,7 @@ ttygetinfo(struct tty *tp, int fromsig,
pick->p_pid);
strlcat(buf, lmsg, bufsz);
- mutex_enter(pick->p_lock);
+ KASSERT(mutex_owned(pick->p_lock));
LIST_FOREACH(l, &pick->p_lwps, l_sibling) {
const char *lp;
lwp_lock(l);
@@ -2679,11 +2696,8 @@ proc_compare_wrapper(struct proc *p1, st
KASSERT(mutex_owned(p1->p_lock));
KASSERT(mutex_owned(p2->p_lock));
- if ((l1 = LIST_FIRST(&p1->p_lwps)) == NULL)
- return 1;
-
- if ((l2 = LIST_FIRST(&p2->p_lwps)) == NULL)
- return 0;
+ l1 = LIST_FIRST(&p1->p_lwps);
+ l2 = LIST_FIRST(&p2->p_lwps);
return proc_compare(p1, l1, p2, l2);
}
