Re: [PATCH] iommu/intel: Fix memleak in intel_irq_remapping_alloc

[Lu Baolu]

On 2021/1/3 12:08, dinghao.liu@xxxxxxxxxx wrote:
> > Hi,
> >
> > On 2021/1/2 17:50, Dinghao Liu wrote:
> > > When irq_domain_get_irq_data() or irqd_cfg() fails
> > > meanwhile i == 0, data allocated by kzalloc() has not
> > > been freed before returning, which leads to memleak.
> > >
> > > Fixes: b106ee63abccb ("irq_remapping/vt-d: Enhance Intel IR driver to support hierarchical irqdomains")
> > > Signed-off-by: Dinghao Liu <dinghao.liu@xxxxxxxxxx>
> > > ---
> > >    drivers/iommu/intel/irq_remapping.c | 2 ++
> > >    1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/iommu/intel/irq_remapping.c b/drivers/iommu/intel/irq_remapping.c
> > > index aeffda92b10b..cdaeed36750f 100644
> > > --- a/drivers/iommu/intel/irq_remapping.c
> > > +++ b/drivers/iommu/intel/irq_remapping.c
> > > @@ -1354,6 +1354,8 @@ static int intel_irq_remapping_alloc(struct irq_domain *domain,
> > >    		irq_cfg = irqd_cfg(irq_data);
> > >    		if (!irq_data || !irq_cfg) {
> > >    			ret = -EINVAL;
> > > +			kfree(data);
> > > +			data = NULL;
> >
> > Do you need to check (i == 0) here? @data will not be used anymore as it
> > goes to out branch, why setting it to NULL here?
>
> data will be passed to ire_data->chip_data when i == 0 and
> intel_free_irq_resources() will free it on failure. Thus I

Isn't it going to "goto out_free_data"? If "i == 0", the allocated @data
won't be freed by intel_free_irq_resources(), hence memory leaking. Does
this patch aim to fix this?

Best regards,
baolu

> set it to NULL to prevent double-free. However, if we add
> a check (i == 0) here, we will not need to set it to NULL.
> If this is better, I will resend a new patch soon.
>
> Regards,
> Dinghao