Re: [PATCH v2] RDMA: release allocated skb

From: Potnuri Bharat Teja
Date: Thu Oct 03 2019 - 06:25:38 EST


On Thursday, October 10/03/19, 2019 at 03:05:06 +0530, Navid Emamdoost wrote:
> Hi Jason,
>
> Thanks for the feedback. Yes, you are right if the skb release is
> moved under err4 label it will cause a double free as
> c4iw_ref_send_wait will release skb in case of error.
> So, in order to avoid leaking skb in case of c4iw_bar2_addrs failure,
> the kfree(skb) could be placed under the error check like the way
> patch v1 did. Do you see any mistake in version 1?
> https://lore.kernel.org/patchwork/patch/1128510/

Hi Navid,
Both the revisions of the patch are invalid. skb is freed in both the cases of
failure and success through c4iw_ofld_send().
case success: in ctrl_xmit()
case failure: in c4iw_ofld_send()

Thanks,
Bharat.


>
>
> Thanks,
> Navid
>
> On Tue, Oct 1, 2019 at 8:54 AM Jason Gunthorpe <jgg@xxxxxxxx> wrote:
> >
> > On Mon, Sep 23, 2019 at 10:52:59AM -0500, Navid Emamdoost wrote:
> > > In create_cq, the allocated skb buffer needs to be released on error
> > > path.
> > > Moved the kfree_skb(skb) under err4 label.
> >
> > This didn't move anything
> >
> > > Signed-off-by: Navid Emamdoost <navid.emamdoost@xxxxxxxxx>
> > > drivers/infiniband/hw/cxgb4/cq.c | 1 +
> > > 1 file changed, 1 insertion(+)
> > >
> > > diff --git a/drivers/infiniband/hw/cxgb4/cq.c b/drivers/infiniband/hw/cxgb4/cq.c
> > > index b1bb61c65f4f..1886c1af10bc 100644
> > > +++ b/drivers/infiniband/hw/cxgb4/cq.c
> > > @@ -173,6 +173,7 @@ static int create_cq(struct c4iw_rdev *rdev, struct t4_cq *cq,
> > > err4:
> > > dma_free_coherent(&rdev->lldi.pdev->dev, cq->memsize, cq->queue,
> > > dma_unmap_addr(cq, mapping));
> > > + kfree_skb(skb);
> > > err3:
> > > kfree(cq->sw_queue);
> > > err2:
> >
> > This looks wrong to me:
> >
> > int c4iw_ofld_send(struct c4iw_rdev *rdev, struct sk_buff *skb)
> > {
> > int error = 0;
> >
> > if (c4iw_fatal_error(rdev)) {
> > kfree_skb(skb);
> > pr_err("%s - device in error state - dropping\n", __func__);
> > return -EIO;
> > }
> > error = cxgb4_ofld_send(rdev->lldi.ports[0], skb);
> > if (error < 0)
> > kfree_skb(skb);
> > return error < 0 ? error : 0;
> > }
> >
> > Jason
>
>
>
> --
> Navid.