Date: Mon, 14 Apr 2003 14:12:39 -0700 From: Marcel Moolenaar <marcel@xcllnt.net> To: John Baldwin <jhb@FreeBSD.org> Cc: current@FreeBSD.org Subject: Re: Bug in rev 1.3 of sys/i386/linux/linux_ptrace.c Message-ID: <20030414211239.GA843@athlon.pn.xcllnt.net> In-Reply-To: <XFMail.20030414161206.jhb@FreeBSD.org> References: <XFMail.20030414161206.jhb@FreeBSD.org>
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On Mon, Apr 14, 2003 at 04:12:06PM -0400, John Baldwin wrote:
> In the linux_ptrace() function there is the following code:
*snip*
> /* not currently stopped */
> if ((p->p_flag & (P_TRACED|P_WAITED)) == 0) {
> error = EBUSY;
> goto fail;
> }
>
> ...
>
> Now, since we've already checked P_TRACED above, this last
> check will never fail. The diff in rev 1.3 was:
>
> - if (p->p_stat != SSTOP || (p->p_flag & P_WAITED) == 0) {
> + if ((p->p_flag & (P_TRACED|P_WAITED)) == 0) {
>
> So should this be (P_STOPPED|P_WAITED) instead? Or maybe just
> (P_STOPPED_TRACE|P_WAITED)?
I don't know the difference between P_STOPPED and P_STOPPED_TRACE
but yes, we should check whether the process is stopped. The
equivalent in sys/kern/sys_process.c is:
if (!P_SHOULDSTOP(p) || (p->p_flag & P_WAITED) == 0) {
P_SHOULDSTOP(p) expands to:
((p)->p_flag & P_STOPPED)
Using P_STOPPED makes us bug-for-bug compatible...
--
Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net
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