ptrace: ptrace_attach: check PF_KTHREAD + exit_state instead of ->mm

[safe/jmp/linux-2.6] / kernel / ptrace.c

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index f6d8b8c..9439bd3 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -172,6 +172,8 @@ int ptrace_attach(struct task_struct *task)
        audit_ptrace(task);
 
        retval = -EPERM;
+       if (unlikely(task->flags & PF_KTHREAD))
+               goto out;
        if (same_thread_group(task, current))
                goto out;
 
@@ -182,8 +184,6 @@ int ptrace_attach(struct task_struct *task)
        retval = mutex_lock_interruptible(&task->cred_guard_mutex);
        if (retval  < 0)
                goto out;
-
-       retval = -EPERM;
 repeat:
        /*
         * Nasty, nasty.
@@ -203,23 +203,24 @@ repeat:
                goto repeat;
        }
 
-       if (!task->mm)
-               goto bad;
-       /* the same process cannot be attached many times */
-       if (task->ptrace & PT_PTRACED)
-               goto bad;
        retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
        if (retval)
                goto bad;
 
-       /* Go */
+       retval = -EPERM;
+       if (unlikely(task->exit_state))
+               goto bad;
+       if (task->ptrace & PT_PTRACED)
+               goto bad;
+
        task->ptrace |= PT_PTRACED;
        if (capable(CAP_SYS_PTRACE))
                task->ptrace |= PT_PTRACE_CAP;
 
        __ptrace_link(task, current);
-
        send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
+
+       retval = 0;
 bad:
        write_unlock_irqrestore(&tasklist_lock, flags);
        task_unlock(task);