[CHECKER] race in 2.5.62/kernel/ptrace.c?

[CHECKER] race in 2.5.62/kernel/ptrace.c?

[Dawson Engler]

Is the following unlocked use of recalc_sigpending  a race?

// 2.5.62/kernel/ptrace.c:339:ptrace_notify:
void ptrace_notify(int exit_code)
{
        BUG_ON (!(current->ptrace & PT_PTRACED));

        /* Let the debugger run.  */
        current->exit_code = exit_code;
        set_current_state(TASK_STOPPED);
        notify_parent(current, SIGCHLD);
        schedule();

        /*
         * Signals sent while we were stopped might set TIF_SIGPENDING.
         */
        recalc_sigpending();
}


It seems that recalc_sigpending needs to be protected by 
	&current->sighand->siglock

E.g.,:

2.5.62/kernel/signal.c:1656:sigprocmask:
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);

2.5.62/kernel/signal.c:2115:sys_sigprocmas

                spin_lock_irq(&current->sighand->siglock);
                old_set = current->blocked.sig[0];

		...

                recalc_sigpending();
                spin_unlock_irq(&current->sighand->siglock);


Or does it not need a lock?  (Or am I missing the lock?)

Re: [CHECKER] race in 2.5.62/kernel/ptrace.c?

[Andrew Morton]

Dawson Engler <engler@csl.stanford.edu> wrote:
>
> Is the following unlocked use of recalc_sigpending  a race?
> 
> // 2.5.62/kernel/ptrace.c:339:ptrace_notify:
> void ptrace_notify(int exit_code)
> {
>         BUG_ON (!(current->ptrace & PT_PTRACED));
> 
>         /* Let the debugger run.  */
>         current->exit_code = exit_code;
>         set_current_state(TASK_STOPPED);
>         notify_parent(current, SIGCHLD);
>         schedule();
> 
>         /*
>          * Signals sent while we were stopped might set TIF_SIGPENDING.
>          */
>         recalc_sigpending();
> }
> 

I think so.  To find out I shall send a patch to Linus and see if
I get shouted at.