From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: [PATCH net 1/3] bpf, mlx5: fix mlx5e_create_rq taking reference on prog Date: Mon, 14 Nov 2016 19:26:29 +0100 Message-ID: <582A01D5.6060608@iogearbox.net> References: <0447a6161550c466ef799b46095440949ffc7df0.1479080215.git.daniel@iogearbox.net> <918902f3-1852-ae68-b12d-eaa1c45bf641@mellanox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: alexei.starovoitov@gmail.com, bblanco@plumgrid.com, tariqt@mellanox.com, zhiyisun@gmail.com, ranas@mellanox.com, netdev@vger.kernel.org To: Saeed Mahameed , davem@davemloft.net Return-path: Received: from www62.your-server.de ([213.133.104.62]:36909 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933225AbcKNS0e (ORCPT ); Mon, 14 Nov 2016 13:26:34 -0500 In-Reply-To: <918902f3-1852-ae68-b12d-eaa1c45bf641@mellanox.com> Sender: netdev-owner@vger.kernel.org List-ID: Hi Saeed, On 11/14/2016 07:15 PM, Saeed Mahameed wrote: > On 11/14/2016 02:43 AM, Daniel Borkmann wrote: >> In mlx5e_create_rq(), when creating a new queue, we call bpf_prog_add() but >> without checking the return value. bpf_prog_add() can fail, so we really > > Didn't know this, thanks for noticing, I wonder why taking a reference for an object would fail ? > especially when someone is requesting from the driver to take a reference to it ndo_xdp_set ?! sounds like a bad design. > > Anyway I will check that later. See 92117d8443bc ("bpf: fix refcnt overflow"). >> must check it. Take the reference right when we assign it to the rq from >> priv->xdp_prog, and just drop the reference on error path. Destruction in >> mlx5e_destroy_rq() looks good, though. >> >> Fixes: 86994156c736 ("net/mlx5e: XDP fast RX drop bpf programs support") >> Signed-off-by: Daniel Borkmann >> --- >> drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 14 +++++++++++--- >> kernel/bpf/syscall.c | 1 + >> 2 files changed, 12 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c >> index 84e8b25..2b83667 100644 >> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c >> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c >> @@ -489,7 +489,16 @@ static int mlx5e_create_rq(struct mlx5e_channel *c, >> rq->channel = c; >> rq->ix = c->ix; >> rq->priv = c->priv; >> + >> rq->xdp_prog = priv->xdp_prog; > > Why keeping this assignment ? just test priv->xdp_prog. > >> + if (rq->xdp_prog) { >> + rq->xdp_prog = bpf_prog_inc(rq->xdp_prog); >> + if (IS_ERR(rq->xdp_prog)) { >> + err = PTR_ERR(rq->xdp_prog); >> + rq->xdp_prog = NULL; >> + goto err_rq_wq_destroy; >> + } >> + } > > Try this, simpler and less indentations: > > rq->xdp_prog = priv->xdp_prog ? bpf_prog_inc(priv->xdp_prog) : NULL; > if (IS_ERR(rq->xdp_prog)) { > err = PTR_ERR(rq->xdp_prog); > rq->xdp_prog = NULL; > goto err_rq_wq_destroy; > } Sure, I don't mind. Will do. Thanks, Daniel