Re: [PATCH v2] RDMA: release allocated skb

From: Navid Emamdoost
Date: Wed Oct 02 2019 - 17:35:21 EST


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/


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.