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ttygetinfo(): avoid crash with zombies. From skrll@, tweaked by me.

This commit is contained in:
ad 2020-01-06 11:18:51 +00:00
parent 6ee4781f70
commit e103824f66
1 changed files with 27 additions and 13 deletions
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40
sys/kern/tty.c
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@ -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, char *buf, size_t bufsz)
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, char *buf, size_t bufsz)
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, char *buf, size_t bufsz)
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, struct proc *p2)
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);
}