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sys_ptrace: fix a locking botch. PR/38649 from Martin Husemann.

This commit is contained in:
yamt 2008-05-13 09:16:11 +00:00
parent 2fd5130380
commit c27d8958e0
1 changed files with 12 additions and 10 deletions
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22
sys/kern/sys_process.c
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@ -1,4 +1,4 @@
/* $NetBSD: sys_process.c,v 1.139 2008/04/28 20:24:04 martin Exp $ */
/* $NetBSD: sys_process.c,v 1.140 2008/05/13 09:16:11 yamt Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@ -115,7 +115,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sys_process.c,v 1.139 2008/04/28 20:24:04 martin Exp $");
__KERNEL_RCSID(0, "$NetBSD: sys_process.c,v 1.140 2008/05/13 09:16:11 yamt Exp $");
#include "opt_coredump.h"
#include "opt_ptrace.h"
@ -614,18 +614,20 @@ sys_ptrace(struct lwp *l, const struct sys_ptrace_args *uap, register_t *retval)
*/
t->p_opptr = t->p_pptr;
if (t->p_pptr != p) {
if (t->p_pptr->p_lock < t->p_lock) {
if (!mutex_tryenter(t->p_pptr->p_lock)) {
struct proc *parent = t->p_pptr;
if (parent->p_lock < t->p_lock) {
if (!mutex_tryenter(parent->p_lock)) {
mutex_exit(t->p_lock);
mutex_enter(t->p_pptr->p_lock);
mutex_enter(parent->p_lock);
}
} else if (t->p_pptr->p_lock > t->p_lock) {
mutex_enter(t->p_pptr->p_lock);
} else if (parent->p_lock > t->p_lock) {
mutex_enter(parent->p_lock);
}
t->p_pptr->p_slflag |= PSL_CHTRACED;
parent->p_slflag |= PSL_CHTRACED;
proc_reparent(t, p);
if (t->p_pptr->p_lock != t->p_lock)
mutex_exit(t->p_pptr->p_lock);
if (parent->p_lock != t->p_lock)
mutex_exit(parent->p_lock);
}
SET(t->p_slflag, PSL_TRACED);
signo = SIGSTOP;