Re: [PATCH 5/7] uretprobes: return probe exit, invoke handlers

[Oleg Nesterov]

The last comment, I promise ;)

On 03/24, Oleg Nesterov wrote:
>
> On 03/22, Anton Arapov wrote:
> >
> > +static void handle_uretprobe(struct xol_area *area, struct pt_regs *regs)
> > +{
> > +	struct uprobe_task *utask;
> > +	struct return_instance *ri, *tmp;
> > +	unsigned long prev_ret_vaddr;
> > +
> > +	utask = get_utask();
> > +	if (!utask)
> > +		return;
> > +
> > +	ri = utask->return_instances;
> > +	if (!ri)
> > +		return;
>
> Hmm. I am wondering what should the caller (handle_swbp) do in this
> case...

And you do not actually need get_utask(), just check current->utask.

handle_uretprobe() must not be called if either ->utask or
->return_instances is NULL. This can only happen if we have a bug,
or user-space tries to fool the kernel.

Perhaps it makes sense to add pr_warn().

Oleg.

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