Fri Jan 3 00:37:30 2020 UTC ()

Correct the rule to iterate over LWPs with PT_LWPNEXT and PT_LWPINFO

Correctly exclude dead/dying/zombie and system threads.

Fixes kern/54802 (gdb -p kills the kernel) by <martin>


(kamil)

diff -r1.76 -r1.77 src/sys/kern/sys_ptrace_common.c

--- src/sys/kern/sys_ptrace_common.c 2019/12/26 08:52:38	1.76
+++ src/sys/kern/sys_ptrace_common.c 2020/01/03 00:37:29	1.77

 @@ -1,14 +1,14 @@
-/*	$NetBSD: sys_ptrace_common.c,v 1.76 2019/12/26 08:52:38 kamil Exp $	*/
+/*	$NetBSD: sys_ptrace_common.c,v 1.77 2020/01/03 00:37:29 kamil Exp $	*/
 /*-
  * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
  * All rights reserved.
+ *
  * This code is derived from software contributed to The NetBSD Foundation
  * by Andrew Doran.
+ *
  * 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.
 @@ -108,27 +108,27 @@
 /*
  * References:
  *	(1) Bach's "The Design of the UNIX Operating System",
  *	(2) sys/miscfs/procfs from UCB's 4.4BSD-Lite distribution,
  *	(3) the "4.4BSD Programmer's Reference Manual" published
  *		by USENIX and O'Reilly & Associates.
  * The 4.4BSD PRM does a reasonably good job of documenting what the various
  * ptrace() requests should actually do, and its text is quoted several times
  * in this file.
  */
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_ptrace_common.c,v 1.76 2019/12/26 08:52:38 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_ptrace_common.c,v 1.77 2020/01/03 00:37:29 kamil Exp $");
 #ifdef _KERNEL_OPT
 #include "opt_ptrace.h"
 #include "opt_ktrace.h"
 #include "opt_pax.h"
 #include "opt_compat_netbsd32.h"
 #endif
 #if defined(__HAVE_COMPAT_NETBSD32) && !defined(COMPAT_NETBSD32) \
     && !defined(_RUMPKERNEL)
 #define COMPAT_NETBSD32
 #endif
 @@ -747,27 +747,28 @@ ptrace_lwpinfo(struct proc *t, struct lw
 	lwp_delref(*lt);
 	mutex_enter(t->p_lock);
 	if (tmp == 0)
 		*lt = lwp_find_first(t);
 	else {
 		*lt = lwp_find(t, tmp);
 		if (*lt == NULL) {
 			mutex_exit(t->p_lock);
 			return ESRCH;
+		}
 		*lt = LIST_NEXT(*lt, l_sibling);
+	}
-	while (*lt != NULL && !lwp_alive(*lt))
+	while (*lt != NULL && (!lwp_alive(*lt) ||
 	       ((*lt)->l_flag & LW_SYSTEM) != 0))
 		*lt = LIST_NEXT(*lt, l_sibling);
 	pl.pl_lwpid = 0;
 	pl.pl_event = 0;
 	if (*lt) {
 		lwp_addref(*lt);
 		pl.pl_lwpid = (*lt)->l_lid;
 		if ((*lt)->l_flag & LW_WSUSPEND)
 			pl.pl_event = PL_EVENT_SUSPENDED;
 		/*
 		 * If we match the lwp, or it was sent to every lwp,
 		 * we set PL_EVENT_SIGNAL.
 @@ -812,28 +813,28 @@ ptrace_lwpstatus(struct proc *t, struct
 		lwpid_t tmp = pls.pl_lwpid;
 		mutex_enter(t->p_lock);
 		if (tmp == 0)
 			*lt = lwp_find_first(t);
 		else {
 			*lt = lwp_find(t, tmp);
 			if (*lt == NULL) {
 				mutex_exit(t->p_lock);
 				return ESRCH;
+			}
 			*lt = LIST_NEXT(*lt, l_sibling);
+		}
-		while (*lt != NULL && !lwp_alive(*lt) &&
+		while (*lt != NULL && (!lwp_alive(*lt) ||
-		       ((*lt)->l_flag & LW_SYSTEM) != 0)
+		       ((*lt)->l_flag & LW_SYSTEM) != 0))
 			*lt = LIST_NEXT(*lt, l_sibling);
 		if (*lt == NULL) {
 			memset(&pls, 0, sizeof(pls));
 			mutex_exit(t->p_lock);
 			goto out;
+		}
 		lwp_addref(*lt);
 		mutex_exit(t->p_lock);
 		pls.pl_lwpid = (*lt)->l_lid;
 	} else {
 		if ((error = ptrace_update_lwp(t, lt, pls.pl_lwpid)) != 0)