Re: + make-good_sigevent-non-static.patch added to -mm tree

[Oleg Nesterov]

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.

This way any user can crash the kernel with a minimal effort.

Oleg.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/