On 01/26, S?bastien Dugu? wrote:
>
> On Thu, 25 Jan 2007 18:43:24 +0300 Oleg Nesterov <[email protected]> wrote:
>
> > SИbastien DuguИ wrote:
> > >
> > > +struct task_struct *good_sigevent(sigevent_t *event)
> > > +{
> > > + struct task_struct *task = current->group_leader;
> > > +
> > > + if ((event->sigev_notify & SIGEV_THREAD_ID) == SIGEV_THREAD_ID) {
> > > + task = find_task_by_pid(event->sigev_notify_thread_id);
> > > +
> > > + if (!task || task->tgid != current->tgid)
> > > + return NULL;
> > > + } else if (event->sigev_notify == SIGEV_SIGNAL) {
> >
> > No, no, we can't use "else" here,
> >
> > > + if (event->sigev_signo <= 0 || event->sigev_signo > SIGRTMAX)
> >
> > because we skip the check above in SIGEV_THREAD_ID case.
>
> Right, will fix this.
>
> >
> > This way any user can crash the kernel with a minimal effort.
>
> Well I tried, no crash, just the signal failing to be delivered.
sigaddset:
set->sig[sig / _NSIG_BPW] |= 1UL << (sig % _NSIG_BPW);
This writes to ->sig[event->sigev_signo / _NSIG_BPW] location, so we can
corrupt the memory if ->sigev_signo > _NSIG.
Btw, since you are exporting this function, may I suggest to rename it?
No, I can't suggest a better name :) But "good_sigevent" is a bit confusing
imho.
Oleg.
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