From: Oleg Nesterov <oleg@redhat.com>

[PATCH] signals: check ->group_stop_count after tracehook_get_signal()

Move the call to do_signal_stop() down, after tracehook call.

This makes ->group_stop_count condition visible to tracers before

do_signal_stop() will participate in this group-stop.

Currently the patch has no effect, tracehook_get_signal() always

returns 0.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Signed-off-by: Roland McGrath <roland@redhat.com>

---

 include/linux/ptrace.h    |    1 +

 include/linux/sched.h     |    1 +

 include/linux/tracehook.h |   10 +++++-----

 kernel/ptrace.c           |    2 +-

 kernel/signal.c           |    4 ++--

 5 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h

index 4272521..a85fb41 100644  

--- a/include/linux/ptrace.h

+++ b/include/linux/ptrace.h

@@ -105,6 +105,7 @@ extern int ptrace_traceme(void);

 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);

 extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);

 extern int ptrace_attach(struct task_struct *tsk);

+extern bool __ptrace_detach(struct task_struct *tracer, struct task_struct *tracee);

 extern int ptrace_detach(struct task_struct *, unsigned int);

 extern void ptrace_disable(struct task_struct *);

 extern int ptrace_check_attach(struct task_struct *task, int kill);

diff --git a/include/linux/sched.h b/include/linux/sched.h

index ce160d6..5e7cc95 100644  

--- a/include/linux/sched.h

+++ b/include/linux/sched.h

@@ -2030,6 +2030,7 @@ extern int kill_pgrp(struct pid *pid, in

 extern int kill_pid(struct pid *pid, int sig, int priv);

 extern int kill_proc_info(int, struct siginfo *, pid_t);

 extern int do_notify_parent(struct task_struct *, int);

+extern void do_notify_parent_cldstop(struct task_struct *, int);

 extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);

 extern void force_sig(int, struct task_struct *);

 extern int send_sig(int, struct task_struct *, int);

diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h

index 10db010..c78b2f4 100644  

--- a/include/linux/tracehook.h

+++ b/include/linux/tracehook.h

@@ -134,7 +134,7 @@ static inline __must_check int tracehook

  */

 static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step)

 {

-	if (step) {

+	if (step && (task_ptrace(current) & PT_PTRACED)) {

 		siginfo_t info;

 		user_single_step_siginfo(current, regs, &info;;

 		force_sig_info(SIGTRAP, &info, current);

@@ -156,7 +156,7 @@ static inline int tracehook_unsafe_exec(

 {

 	int unsafe = 0;

 	int ptrace = task_ptrace(task);

-	if (ptrace & PT_PTRACED) {

+	if (ptrace) {

 		if (ptrace & PT_PTRACE_CAP)

 			unsafe |= LSM_UNSAFE_PTRACE_CAP;

 		else

@@ -178,7 +178,7 @@ static inline int tracehook_unsafe_exec(

  */

 static inline struct task_struct *tracehook_tracer_task(struct task_struct *tsk)

 {

-	if (task_ptrace(tsk) & PT_PTRACED)

+	if (task_ptrace(tsk))

 		return rcu_dereference(tsk->parent);

 	return NULL;

 }

@@ -386,7 +386,7 @@ static inline void tracehook_signal_hand

 					    const struct k_sigaction *ka,

 					    struct pt_regs *regs, int stepping)

 {

-	if (stepping)

+	if (stepping && (task_ptrace(current) & PT_PTRACED))

 		ptrace_notify(SIGTRAP);

 }

@@ -492,7 +492,7 @@ static inline int tracehook_get_signal(s

  */

 static inline int tracehook_notify_jctl(int notify, int why)

 {

-	return notify ?: (current->ptrace & PT_PTRACED) ? why : 0;

+	return notify ?: task_ptrace(current) ? why : 0;

 }

 /**

diff --git a/kernel/ptrace.c b/kernel/ptrace.c

index f34d798..8049cb5 100644  

--- a/kernel/ptrace.c

+++ b/kernel/ptrace.c

@@ -270,7 +270,7 @@ static int ignoring_children(struct sigh

  * reap it now, in that case we must also wake up sub-threads sleeping in

  * do_wait().

  */

-static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)

+bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)

 {

 	__ptrace_unlink(p);

diff --git a/kernel/signal.c b/kernel/signal.c

index bded651..6d13d9f 100644  

--- a/kernel/signal.c

+++ b/kernel/signal.c

@@ -1521,7 +1521,7 @@ int do_notify_parent(struct task_struct 

 	return ret;

 }

-static void do_notify_parent_cldstop(struct task_struct *tsk, int why)

+void do_notify_parent_cldstop(struct task_struct *tsk, int why)

 {

 	struct siginfo info;

 	unsigned long flags;

@@ -1791,7 +1791,7 @@ static int do_signal_stop(int signr)

 static int ptrace_signal(int signr, siginfo_t *info,

 			 struct pt_regs *regs, void *cookie)

 {

-	if (!task_ptrace(current))

+	if (!(task_ptrace(current) & PT_PTRACED))

 		return signr;

 	ptrace_signal_deliver(regs, cookie);