Fix ptrace self-attach rule

Before we did CLONE_THREAD, the way to check whether we were attaching
to ourselves was to just check "current == task", but with CLONE_THREAD
we should check that the thread group ID matches instead.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 5b8dd98a230e442c1ec46adc968acb60dfdb74ae..b88d4186cd7ac2733c3adf231d5b4daa4e14b0a9 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -155,7 +155,7 @@ int ptrace_attach(struct task_struct *task)
        retval = -EPERM;
        if (task->pid <= 1)
                goto bad;
-       if (task == current)
+       if (task->tgid == current->tgid)
                goto bad;
        /* the same process cannot be attached many times */
        if (task->ptrace & PT_PTRACED)