svn commit: r304487 - in head/sys: kern sys

[Mark Johnston]

Author: markj
Date: Fri Aug 19 17:57:14 2016
New Revision: 304487
URL: https://svnweb.freebsd.org/changeset/base/304487

Log:
  Don't set P2_PTRACE_FSTP in a process that invokes ptrace(PT_TRACE_ME).
  
  Such processes are stopped synchronously by a direct call to
  ptracestop(SIGTRAP) upon exec. P2_PTRACE_FSTP causes the exec()ing thread
  to suspend itself while waiting for a SIGSTOP that never arrives.
  
  Reviewed by:	kib
  MFC after:	3 days
  Differential Revision:	https://reviews.freebsd.org/D7576

Modified:
  head/sys/kern/kern_fork.c
  head/sys/kern/sys_process.c
  head/sys/sys/proc.h

Modified: head/sys/kern/kern_fork.c
==============================================================================
--- head/sys/kern/kern_fork.c	Fri Aug 19 17:55:34 2016	(r304486)
+++ head/sys/kern/kern_fork.c	Fri Aug 19 17:57:14 2016	(r304487)
@@ -1074,7 +1074,7 @@ fork_return(struct thread *td, struct tr
 			 * parent's children, do it now.
 			 */
 			dbg = p->p_pptr->p_pptr;
-			proc_set_traced(p);
+			proc_set_traced(p, true);
 			CTR2(KTR_PTRACE,
 		    "fork_return: attaching to new child pid %d: oppid %d",
 			    p->p_pid, p->p_oppid);

Modified: head/sys/kern/sys_process.c
==============================================================================
--- head/sys/kern/sys_process.c	Fri Aug 19 17:55:34 2016	(r304486)
+++ head/sys/kern/sys_process.c	Fri Aug 19 17:57:14 2016	(r304487)
@@ -693,12 +693,13 @@ sys_ptrace(struct thread *td, struct ptr
 #endif
 
 void
-proc_set_traced(struct proc *p)
+proc_set_traced(struct proc *p, bool stop)
 {
 
 	PROC_LOCK_ASSERT(p, MA_OWNED);
 	p->p_flag |= P_TRACED;
-	p->p_flag2 |= P2_PTRACE_FSTP;
+	if (stop)
+		p->p_flag2 |= P2_PTRACE_FSTP;
 	p->p_ptevents = PTRACE_DEFAULT;
 	p->p_oppid = p->p_pptr->p_pid;
 }
@@ -910,7 +911,7 @@ kern_ptrace(struct thread *td, int req, 
 	switch (req) {
 	case PT_TRACE_ME:
 		/* set my trace flag and "owner" so it can read/write me */
-		proc_set_traced(p);
+		proc_set_traced(p, false);
 		if (p->p_flag & P_PPWAIT)
 			p->p_flag |= P_PPTRACE;
 		CTR1(KTR_PTRACE, "PT_TRACE_ME: pid %d", p->p_pid);
@@ -927,7 +928,7 @@ kern_ptrace(struct thread *td, int req, 
 		 * The old parent is remembered so we can put things back
 		 * on a "detach".
 		 */
-		proc_set_traced(p);
+		proc_set_traced(p, true);
 		if (p->p_pptr != td->td_proc) {
 			proc_reparent(p, td->td_proc);
 		}

Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h	Fri Aug 19 17:55:34 2016	(r304486)
+++ head/sys/sys/proc.h	Fri Aug 19 17:57:14 2016	(r304487)
@@ -1010,7 +1010,7 @@ void	proc_linkup(struct proc *p, struct 
 struct proc *proc_realparent(struct proc *child);
 void	proc_reap(struct thread *td, struct proc *p, int *status, int options);
 void	proc_reparent(struct proc *child, struct proc *newparent);
-void	proc_set_traced(struct proc *p);
+void	proc_set_traced(struct proc *p, bool stop);
 struct	pstats *pstats_alloc(void);
 void	pstats_fork(struct pstats *src, struct pstats *dst);
 void	pstats_free(struct pstats *ps);