From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: [PATCH] net: mlx5: fix a potential NULL pointer dereference Date: Mon, 11 Mar 2019 11:06:37 -0300 Message-ID: <20190311140637.GI22848@ziepe.ca> References: <20190311063343.20188-1-kjlu@umn.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190311063343.20188-1-kjlu@umn.edu> Sender: linux-kernel-owner@vger.kernel.org To: Kangjie Lu Cc: pakki001@umn.edu, Saeed Mahameed , Leon Romanovsky , "David S. Miller" , netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-rdma@vger.kernel.org On Mon, Mar 11, 2019 at 01:33:43AM -0500, Kangjie Lu wrote: > In case skb_header_pointer fails, the fix issues a warning. > > A better fix requires modifying the signature of mlx5e_get_fcs to > pass an error code upstream. > > Signed-off-by: Kangjie Lu > drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c > index be396e5e4e39..6ec1c110e4be 100644 > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c > @@ -719,6 +719,8 @@ static u32 mlx5e_get_fcs(const struct sk_buff *skb) > > fcs_bytes = skb_header_pointer(skb, skb->len - ETH_FCS_LEN, > ETH_FCS_LEN, &_fcs_bytes); > + if (unlikely(!fcs_bytes)) > + pr_warn_once("skb_header_pointer returns NULL\n"); This is really pointless. Fix stuff like this so it doesn't oops or don't bother. Jason > return __get_unaligned_cpu32(fcs_bytes); > }