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Only reparent a traced process to its old parent if the tracing process is

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not the old parent. Otherwise, proc_reap() will leave the zombie in place
resulting in the process' status being returned twice to its parent.

Add test cases for PT_TRACE_ME and PT_ATTACH which are fixed by
this change.

Differential Revision:	https://reviews.freebsd.org/D2594
Reviewed by:	kib
MFC after:	2 weeks
This commit is contained in:
John Baldwin 2015-05-22 11:04:54 +00:00
parent 312827253b
commit c209e3e2e6
3 changed files with 148 additions and 2 deletions
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6
sys/kern/kern_exit.c
View File

@ -847,13 +847,13 @@ proc_reap(struct thread *td, struct proc *p, int *status, int options)
PROC_LOCK(q);
sigqueue_take(p->p_ksi);
PROC_UNLOCK(q);
PROC_UNLOCK(p);
/*
* If we got the child via a ptrace 'attach', we need to give it back
* to the old parent.
*/
if (p->p_oppid != 0) {
if (p->p_oppid != 0 && p->p_oppid != p->p_pptr->p_pid) {
PROC_UNLOCK(p);
t = proc_realparent(p);
PROC_LOCK(t);
PROC_LOCK(p);
@ -867,6 +867,8 @@ proc_reap(struct thread *td, struct proc *p, int *status, int options)
sx_xunlock(&proctree_lock);
return;
}
p->p_oppid = 0;
PROC_UNLOCK(p);
/*
* Remove other references to this process to ensure we have an

1
tests/sys/kern/Makefile
View File

@ -3,6 +3,7 @@
TESTSDIR= ${TESTSBASE}/sys/kern
ATF_TESTS_C+= kern_descrip_test
ATF_TESTS_C+= ptrace_test
ATF_TESTS_C+= unix_seqpacket_test
TEST_METADATA.unix_seqpacket_test+= timeout="15"

143
tests/sys/kern/ptrace_test.c Normal file
View File

@ -0,0 +1,143 @@
/*-
* Copyright (c) 2015 John Baldwin <jhb@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <errno.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <atf-c.h>
/*
* Verify that a parent debugger process "sees" the exit of a debugged
* process exactly once when attached via PT_TRACE_ME.
*/
ATF_TC_WITHOUT_HEAD(ptrace__parent_wait_after_trace_me);
ATF_TC_BODY(ptrace__parent_wait_after_trace_me, tc)
{
pid_t child, wpid;
int status;
ATF_REQUIRE((child = fork()) != -1);
if (child == 0) {
/* Child process. */
ATF_REQUIRE(ptrace(PT_TRACE_ME, 0, NULL, 0) != -1);
/* Trigger a stop. */
raise(SIGSTOP);
exit(1);
}
/* Parent process. */
/* The first wait() should report the stop from SIGSTOP. */
wpid = waitpid(child, &status, 0);
ATF_REQUIRE(wpid == child);
ATF_REQUIRE(WIFSTOPPED(status));
ATF_REQUIRE(WSTOPSIG(status) == SIGSTOP);
/* Continue the child ignoring the SIGSTOP. */
ATF_REQUIRE(ptrace(PT_CONTINUE, child, (caddr_t)1, 0) != -1);
/* The second wait() should report the exit status. */
wpid = waitpid(child, &status, 0);
ATF_REQUIRE(wpid == child);
ATF_REQUIRE(WIFEXITED(status));
ATF_REQUIRE(WEXITSTATUS(status) == 1);
/* The child should no longer exist. */
wpid = waitpid(child, &status, 0);
ATF_REQUIRE(wpid == -1);
ATF_REQUIRE(errno == ECHILD);
}
/*
* Verify that a parent debugger process "sees" the exit of a debugged
* process exactly once when attached via PT_ATTACH.
*/
ATF_TC_WITHOUT_HEAD(ptrace__parent_wait_after_attach);
ATF_TC_BODY(ptrace__parent_wait_after_attach, tc)
{
pid_t child, wpid;
int cpipe[2], status;
char c;
ATF_REQUIRE(pipe(cpipe) == 0);
ATF_REQUIRE((child = fork()) != -1);
if (child == 0) {
/* Child process. */
close(cpipe[0]);
/* Wait for the parent to attach. */
ATF_REQUIRE(read(cpipe[1], &c, sizeof(c)) == 0);
exit(1);
}
close(cpipe[1]);
/* Parent process. */
/* Attach to the child process. */
ATF_REQUIRE(ptrace(PT_ATTACH, child, NULL, 0) == 0);
/* The first wait() should report the SIGSTOP from PT_ATTACH. */
wpid = waitpid(child, &status, 0);
ATF_REQUIRE(wpid == child);
ATF_REQUIRE(WIFSTOPPED(status));
ATF_REQUIRE(WSTOPSIG(status) == SIGSTOP);
/* Continue the child ignoring the SIGSTOP. */
ATF_REQUIRE(ptrace(PT_CONTINUE, child, (caddr_t)1, 0) != -1);
/* Signal the child to exit. */
close(cpipe[0]);
/* The second wait() should report the exit status. */
wpid = waitpid(child, &status, 0);
ATF_REQUIRE(wpid == child);
ATF_REQUIRE(WIFEXITED(status));
ATF_REQUIRE(WEXITSTATUS(status) == 1);
/* The child should no longer exist. */
wpid = waitpid(child, &status, 0);
ATF_REQUIRE(wpid == -1);
ATF_REQUIRE(errno == ECHILD);
}
ATF_TP_ADD_TCS(tp)
{
ATF_TP_ADD_TC(tp, ptrace__parent_wait_after_trace_me);
ATF_TP_ADD_TC(tp, ptrace__parent_wait_after_attach);
return (atf_no_error());
}