svn commit: r346009 - in head: sys/kern tests/sys/kern

Mark Johnston markj at FreeBSD.org
Sun Apr 7 14:26:16 UTC 2019


Author: markj
Date: Sun Apr  7 14:26:14 2019
New Revision: 346009
URL: https://svnweb.freebsd.org/changeset/base/346009

Log:
  Set the p_oppid field of orphans when exiting.
  
  Such processes will be reparented to the reaper when the current
  parent is done with them (i.e., ptrace detached), so p_oppid must be
  updated accordingly.
  
  Add a regression test to exercise this code path.  Previously it
  would not be possible to reap an orphan with a stale oppid.
  
  Reviewed by:	kib, mjg
  Tested by:	pho
  MFC after:	2 weeks
  Sponsored by:	The FreeBSD Foundation
  Differential Revision:	https://reviews.freebsd.org/D19825

Modified:
  head/sys/kern/kern_exit.c
  head/tests/sys/kern/ptrace_test.c

Modified: head/sys/kern/kern_exit.c
==============================================================================
--- head/sys/kern/kern_exit.c	Sun Apr  7 14:07:28 2019	(r346008)
+++ head/sys/kern/kern_exit.c	Sun Apr  7 14:26:14 2019	(r346009)
@@ -543,6 +543,11 @@ exit1(struct thread *td, int rval, int signo)
 	 */
 	while ((q = LIST_FIRST(&p->p_orphans)) != NULL) {
 		PROC_LOCK(q);
+		KASSERT(q->p_oppid == p->p_pid,
+		    ("orphan %p of %p has unexpected oppid %d", q, p,
+		    q->p_oppid));
+		q->p_oppid = q->p_reaper->p_pid;
+
 		/*
 		 * If we are the real parent of this process
 		 * but it has been reparented to a debugger, then

Modified: head/tests/sys/kern/ptrace_test.c
==============================================================================
--- head/tests/sys/kern/ptrace_test.c	Sun Apr  7 14:07:28 2019	(r346008)
+++ head/tests/sys/kern/ptrace_test.c	Sun Apr  7 14:26:14 2019	(r346009)
@@ -452,6 +452,67 @@ ATF_TC_BODY(ptrace__parent_sees_exit_after_unrelated_d
 }
 
 /*
+ * Make sure that we can collect the exit status of an orphaned process.
+ */
+ATF_TC_WITHOUT_HEAD(ptrace__parent_exits_before_child);
+ATF_TC_BODY(ptrace__parent_exits_before_child, tc)
+{
+	ssize_t n;
+	int cpipe1[2], cpipe2[2], gcpipe[2], status;
+	pid_t child, gchild;
+
+	ATF_REQUIRE(pipe(cpipe1) == 0);
+	ATF_REQUIRE(pipe(cpipe2) == 0);
+	ATF_REQUIRE(pipe(gcpipe) == 0);
+
+	ATF_REQUIRE(procctl(P_PID, getpid(), PROC_REAP_ACQUIRE, NULL) == 0);
+
+	ATF_REQUIRE((child = fork()) != -1);
+	if (child == 0) {
+		CHILD_REQUIRE((gchild = fork()) != -1);
+		if (gchild == 0) {
+			status = 1;
+			do {
+				n = read(gcpipe[0], &status, sizeof(status));
+			} while (n == -1 && errno == EINTR);
+			_exit(status);
+		}
+
+		CHILD_REQUIRE(write(cpipe1[1], &gchild, sizeof(gchild)) ==
+		    sizeof(gchild));
+		CHILD_REQUIRE(read(cpipe2[0], &status, sizeof(status)) ==
+		    sizeof(status));
+		_exit(status);
+	}
+
+	ATF_REQUIRE(read(cpipe1[0], &gchild, sizeof(gchild)) == sizeof(gchild));
+
+	ATF_REQUIRE(ptrace(PT_ATTACH, gchild, NULL, 0) == 0);
+
+	status = 0;
+	ATF_REQUIRE(write(cpipe2[1], &status, sizeof(status)) ==
+	    sizeof(status));
+	ATF_REQUIRE(waitpid(child, &status, 0) == child);
+	ATF_REQUIRE(WIFEXITED(status) && WEXITSTATUS(status) == 0);
+
+	status = 0;
+	ATF_REQUIRE(write(gcpipe[1], &status, sizeof(status)) ==
+	    sizeof(status));
+	ATF_REQUIRE(waitpid(gchild, &status, 0) == gchild);
+	ATF_REQUIRE(WIFSTOPPED(status));
+	ATF_REQUIRE(ptrace(PT_DETACH, gchild, (caddr_t)1, 0) == 0);
+	ATF_REQUIRE(waitpid(gchild, &status, 0) == gchild);
+	ATF_REQUIRE(WIFEXITED(status) && WEXITSTATUS(status) == 0);
+
+	ATF_REQUIRE(close(cpipe1[0]) == 0);
+	ATF_REQUIRE(close(cpipe1[1]) == 0);
+	ATF_REQUIRE(close(cpipe2[0]) == 0);
+	ATF_REQUIRE(close(cpipe2[1]) == 0);
+	ATF_REQUIRE(close(gcpipe[0]) == 0);
+	ATF_REQUIRE(close(gcpipe[1]) == 0);
+}
+
+/*
  * The parent process should always act the same regardless of how the
  * debugger is attached to it.
  */
@@ -3850,6 +3911,7 @@ ATF_TP_ADD_TCS(tp)
 	ATF_TP_ADD_TC(tp, ptrace__parent_wait_after_attach);
 	ATF_TP_ADD_TC(tp, ptrace__parent_sees_exit_after_child_debugger);
 	ATF_TP_ADD_TC(tp, ptrace__parent_sees_exit_after_unrelated_debugger);
+	ATF_TP_ADD_TC(tp, ptrace__parent_exits_before_child);
 	ATF_TP_ADD_TC(tp, ptrace__follow_fork_both_attached);
 	ATF_TP_ADD_TC(tp, ptrace__follow_fork_child_detached);
 	ATF_TP_ADD_TC(tp, ptrace__follow_fork_parent_detached);


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