Re: FW: [PATCH] RDMA/rxe: Fix possible NULL pointer dereference

[Zhu Yanjun]

On Wed, Oct 14, 2020 at 8:34 AM Yanjun Zhu <yanjunz@xxxxxxxxxx> wrote:
>
>
>
> -----Original Message-----
> From: Alex Dewar <alex.dewar90@xxxxxxxxx>
> Sent: Tuesday, October 13, 2020 12:53 AM
> Cc: Alex Dewar <alex.dewar90@xxxxxxxxx>; Yanjun Zhu <yanjunz@xxxxxxxxxx>; Doug Ledford <dledford@xxxxxxxxxx>; Jason Gunthorpe <jgg@xxxxxxxx>; Bob Pearson <rpearsonhpe@xxxxxxxxx>; linux-rdma@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: [PATCH] RDMA/rxe: Fix possible NULL pointer dereference
>
> skb_clone() is called without checking if the returned pointer is NULL before it is dereferenced. Fix by adding an additional error check.
>
> Fixes: e7ec96fc7932 ("RDMA/rxe: Fix skb lifetime in rxe_rcv_mcast_pkt()")
> Addresses-Coverity-ID: 1497804: Null pointer dereferences (NULL_RETURNS)
> Signed-off-by: Alex Dewar <alex.dewar90@xxxxxxxxx>

Thanks a lot.

Zhu Yanjun
> ---
>  drivers/infiniband/sw/rxe/rxe_recv.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
> index 11f3daf20768..a65936e12f89 100644
> --- a/drivers/infiniband/sw/rxe/rxe_recv.c
> +++ b/drivers/infiniband/sw/rxe/rxe_recv.c
> @@ -266,10 +266,13 @@ static void rxe_rcv_mcast_pkt(struct rxe_dev *rxe, struct sk_buff *skb)
>                 /* for all but the last qp create a new clone of the
>                  * skb and pass to the qp.
>                  */
> -               if (mce->qp_list.next != &mcg->qp_list)
> +               if (mce->qp_list.next != &mcg->qp_list) {
>                         per_qp_skb = skb_clone(skb, GFP_ATOMIC);
> -               else
> +                       if (!per_qp_skb)
> +                               goto err2;
> +               } else {
>                         per_qp_skb = skb;
> +               }
>
>                 per_qp_pkt = SKB_TO_PKT(per_qp_skb);
>                 per_qp_pkt->qp = qp;
> @@ -283,6 +286,10 @@ static void rxe_rcv_mcast_pkt(struct rxe_dev *rxe, struct sk_buff *skb)
>
>         return;
>
> +err2:
> +       spin_unlock_bh(&mcg->mcg_lock);
> +       rxe_drop_ref(mcg);      /* drop ref from rxe_pool_get_key. */
> +
>  err1:
>         kfree_skb(skb);
>  }
> --
> 2.28.0
>