Merge branch 'master' into next

1 files changed, 101 insertions, 29 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index c9cf48b21f05..0692ab5a0d67 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);