2019-09-25 19:26:46

by Navid Emamdoost

Subject: [PATCH v2] RDMA: release allocated skb

In create_cq, the allocated skb buffer needs to be released on error
path.
Moved the kfree_skb(skb) under err4 label.

Signed-off-by: Navid Emamdoost <[email protected]>
---
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
--- a/drivers/infiniband/hw/cxgb4/cq.c
+++ 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:
--
2.17.1

2019-10-01 13:56:28

by Jason Gunthorpe

Subject: Re: [PATCH v2] RDMA: release allocated skb

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 <[email protected]>
> 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

2019-10-02 21:58:22

by Navid Emamdoost

Subject: Re: [PATCH v2] RDMA: release allocated skb

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 <[email protected]> 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 <[email protected]>
> > 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.

2019-10-03 08:21:52

by Leon Romanovsky

Subject: Re: [PATCH v2] RDMA: release allocated skb

On Wed, Oct 02, 2019 at 04:35:06PM -0500, 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/

No, it is not enough.
c4iw_ref_send_wait() ->
c4iw_wait_for_reply() ->
return wr_waitp->ret; <--- can be -EIO

Thanks

2019-10-03 10:27:06

by Potnuri Bharat Teja

Subject: Re: [PATCH v2] RDMA: release allocated skb

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 <[email protected]> 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 <[email protected]>
> > > 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.

2019-10-04 18:19:13

by Navid Emamdoost

Subject: Re: [PATCH v2] RDMA: release allocated skb

Hi Leon and Potnuri,

Based on the following call sequence, skb is passed along to uld_send().
c4iw_ref_send_wait
c4iw_ofld_send
cxgb4_ofld_send
t4_ofld_send
uld_send

In uld_send() skb is consumed (released or added to queue) via
ctrl_xmit() or ofld_xmit(), which assures no leak is happening. But in
the condition check for txq_info the return value is NET_XMIT_DROP
which means the skb should be released. Here I believe skb is being
leaked:

txq_info = adap->sge.uld_txq_info[tx_uld_type];
if (unlikely(!txq_info)) {
WARN_ON(true);
return NET_XMIT_DROP;
}

Please let me know what you think, then I can go ahead and fix the patch.

Thank you,
Navid.

On Thu, Oct 3, 2019 at 5:25 AM Potnuri Bharat Teja <[email protected]> wrote:
>
> 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 <[email protected]> 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 <[email protected]>
> > > > 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.



--
Navid.