Merge branch 'master' into next

1 files changed, 101 insertions, 29 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index c9cf48b21f0..0692ab5a0d6 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -21,9 +21,7 @@
 #include <linux/audit.h>
 #include <linux/pid_namespace.h>
 #include <linux/syscalls.h>
-
-#include <asm/pgtable.h>
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
 
 
 /*
@@ -48,7 +46,7 @@ void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
 	list_add(&child->ptrace_entry, &new_parent->ptraced);
 	child->parent = new_parent;
 }
- 
+
 /*
  * Turn a tracing stop into a normal stop now, since with no tracer there
  * would be no way to wake it up with SIGCONT or SIGKILL.  If there was a
@@ -60,11 +58,15 @@ static void ptrace_untrace(struct task_struct *child)
 {
 	spin_lock(&child->sighand->siglock);
 	if (task_is_traced(child)) {
-		if (child->signal->flags & SIGNAL_STOP_STOPPED) {
+		/*
+		 * If the group stop is completed or in progress,
+		 * this thread was already counted as stopped.
+		 */
+		if (child->signal->flags & SIGNAL_STOP_STOPPED ||
+		    child->signal->group_stop_count)
 			__set_task_state(child, TASK_STOPPED);
-		} else {
+		else
 			signal_wake_up(child, 1);
-		}
 	}
 	spin_unlock(&child->sighand->siglock);
 }
@@ -169,7 +171,7 @@ bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 	task_lock(task);
 	err = __ptrace_may_access(task, mode);
 	task_unlock(task);
-	return (!err ? true : false);
+	return !err;
 }
 
 int ptrace_attach(struct task_struct *task)
@@ -186,7 +188,7 @@ int ptrace_attach(struct task_struct *task)
 	/* Protect exec's credential calculations against our interference;
 	 * SUID, SGID and LSM creds get determined differently under ptrace.
 	 */
-	retval = mutex_lock_interruptible(&current->cred_exec_mutex);
+	retval = mutex_lock_interruptible(&task->cred_exec_mutex);
 	if (retval  < 0)
 		goto out;
 
@@ -230,23 +232,63 @@ repeat:
 bad:
 	write_unlock_irqrestore(&tasklist_lock, flags);
 	task_unlock(task);
-	mutex_unlock(&current->cred_exec_mutex);
+	mutex_unlock(&task->cred_exec_mutex);
 out:
 	return retval;
 }
 
-static inline void __ptrace_detach(struct task_struct *child, unsigned int data)
+/*
+ * Called with irqs disabled, returns true if childs should reap themselves.
+ */
+static int ignoring_children(struct sighand_struct *sigh)
 {
-	child->exit_code = data;
-	/* .. re-parent .. */
-	__ptrace_unlink(child);
-	/* .. and wake it up. */
-	if (child->exit_state != EXIT_ZOMBIE)
-		wake_up_process(child);
+	int ret;
+	spin_lock(&sigh->siglock);
+	ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
+	      (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
+	spin_unlock(&sigh->siglock);
+	return ret;
+}
+
+/*
+ * Called with tasklist_lock held for writing.
+ * Unlink a traced task, and clean it up if it was a traced zombie.
+ * Return true if it needs to be reaped with release_task().
+ * (We can't call release_task() here because we already hold tasklist_lock.)
+ *
+ * If it's a zombie, our attachedness prevented normal parent notification
+ * or self-reaping.  Do notification now if it would have happened earlier.
+ * If it should reap itself, return true.
+ *
+ * If it's our own child, there is no notification to do.
+ * But if our normal children self-reap, then this child
+ * was prevented by ptrace and we must reap it now.
+ */
+static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
+{
+	__ptrace_unlink(p);
+
+	if (p->exit_state == EXIT_ZOMBIE) {
+		if (!task_detached(p) && thread_group_empty(p)) {
+			if (!same_thread_group(p->real_parent, tracer))
+				do_notify_parent(p, p->exit_signal);
+			else if (ignoring_children(tracer->sighand))
+				p->exit_signal = -1;
+		}
+		if (task_detached(p)) {
+			/* Mark it as in the process of being reaped. */
+			p->exit_state = EXIT_DEAD;
+			return true;
+		}
+	}
+
+	return false;
 }
 
 int ptrace_detach(struct task_struct *child, unsigned int data)
 {
+	bool dead = false;
+
 	if (!valid_signal(data))
 		return -EIO;
 
@@ -255,14 +297,45 @@ int ptrace_detach(struct task_struct *child, unsigned int data)
 	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 
 	write_lock_irq(&tasklist_lock);
-	/* protect against de_thread()->release_task() */
-	if (child->ptrace)
-		__ptrace_detach(child, data);
+	/*
+	 * This child can be already killed. Make sure de_thread() or
+	 * our sub-thread doing do_wait() didn't do release_task() yet.
+	 */
+	if (child->ptrace) {
+		child->exit_code = data;
+		dead = __ptrace_detach(current, child);
+	}
 	write_unlock_irq(&tasklist_lock);
 
+	if (unlikely(dead))
+		release_task(child);
+
 	return 0;
 }
 
+/*
+ * Detach all tasks we were using ptrace on.
+ */
+void exit_ptrace(struct task_struct *tracer)
+{
+	struct task_struct *p, *n;
+	LIST_HEAD(ptrace_dead);
+
+	write_lock_irq(&tasklist_lock);
+	list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
+		if (__ptrace_detach(tracer, p))
+			list_add(&p->ptrace_entry, &ptrace_dead);
+	}
+	write_unlock_irq(&tasklist_lock);
+
+	BUG_ON(!list_empty(&tracer->ptraced));
+
+	list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
+		list_del_init(&p->ptrace_entry);
+		release_task(p);
+	}
+}
+
 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
 {
 	int copied = 0;
@@ -283,7 +356,7 @@ int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst
 		copied += retval;
 		src += retval;
 		dst += retval;
-		len -= retval;			
+		len -= retval;
 	}
 	return copied;
 }
@@ -308,7 +381,7 @@ int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long ds
 		copied += retval;
 		src += retval;
 		dst += retval;
-		len -= retval;			
+		len -= retval;
 	}
 	return copied;
 }
@@ -421,9 +494,9 @@ static int ptrace_resume(struct task_struct *child, long request, long data)
 		if (unlikely(!arch_has_single_step()))
 			return -EIO;
 		user_enable_single_step(child);
-	}
-	else
+	} else {
 		user_disable_single_step(child);
+	}
 
 	child->exit_code = data;
 	wake_up_process(child);
@@ -531,10 +604,11 @@ repeat:
 		ret = security_ptrace_traceme(current->parent);
 
 		/*
-		 * Set the ptrace bit in the process ptrace flags.
-		 * Then link us on our parent's ptraced list.
+		 * Check PF_EXITING to ensure ->real_parent has not passed
+		 * exit_ptrace(). Otherwise we don't report the error but
+		 * pretend ->real_parent untraces us right after return.
 		 */
-		if (!ret) {
+		if (!ret && !(current->real_parent->flags & PF_EXITING)) {
 			current->ptrace |= PT_PTRACED;
 			__ptrace_link(current, current->real_parent);
 		}
@@ -612,8 +686,6 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
 		goto out_put_task_struct;
 
 	ret = arch_ptrace(child, request, addr, data);
-	if (ret < 0)
-		goto out_put_task_struct;
 
  out_put_task_struct:
 	put_task_struct(child);