Re: [PATCH] USB: whci-hcd: add more checks for dma mapping error

[Alexey Khoroshilov]

On 26.03.2016 01:03, Vladimir Zapolskiy wrote:
> On 25.03.2016 22:23, Alexey Khoroshilov wrote:
> > Fixing checks for dma mapping error in qset_fill_page_list(),
> > I have missed two similar problems in qset_add_urb_sg() and
> > in qset_add_urb_sg_linearize().
> >
> > Found by Linux Driver Verification project (linuxtesting.org).
> >
> > Signed-off-by: Alexey Khoroshilov <khoroshilov@xxxxxxxxx>
> > ---
> >   drivers/usb/host/whci/qset.c | 6 +++++-
> >   1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/host/whci/qset.c b/drivers/usb/host/whci/qset.c
> > index 1a8e960d073b..a8e9b618e643 100644
> > --- a/drivers/usb/host/whci/qset.c
> > +++ b/drivers/usb/host/whci/qset.c
> > @@ -535,9 +535,11 @@ static int qset_add_urb_sg(struct whc *whc, struct whc_qset *qset, struct urb *u
> >   	list_for_each_entry(std, &qset->stds, list_node) {
> >   		if (std->ntds_remaining == -1) {
> >   			pl_len = std->num_pointers * sizeof(struct whc_page_list_entry);
> > -			std->ntds_remaining = ntds--;
> >   			std->dma_addr = dma_map_single(whc->wusbhc.dev, std->pl_virt,
> >   						       pl_len, DMA_TO_DEVICE);
> > +			if (dma_mapping_error(whc->wusbhc.dev, std->dma_addr))
> > +				return -EFAULT;
>
> Resources are leaked on error path:
> * std->pl_virt  -- most probably, at least it is freed on error path above,
> * dma mappings done in a loop before met error,

As far as I can see, it is not the case.
If qset_add_urb_sg() returns error code, the caller (qset_add_urb()) 
invokes qset_free_stds() that performs all resource deallocations.

As for the error path above, I consider it as a typical krealloc() 
pattern, since it does not frees memory allocated at previous iterations 
of the cycle.

Thank you,
Alexey