netdev - RE: [PATCH net v2 4/5] dpaa_eth: execute xdp_do_flush() before napi_complete

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <VI1PR04MB58072AA61FA976FE67EA0511F2CE9@VI1PR04MB5807.eurprd04.prod.outlook.com>
Date:   Wed, 25 Jan 2023 14:58:56 +0000
From:   Camelia Alexandra Groza <camelia.groza@....com>
To:     Magnus Karlsson <magnus.karlsson@...il.com>,
        "magnus.karlsson@...el.com" <magnus.karlsson@...el.com>,
        "bjorn@...nel.org" <bjorn@...nel.org>,
        "ast@...nel.org" <ast@...nel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "jonathan.lemon@...il.com" <jonathan.lemon@...il.com>,
        "maciej.fijalkowski@...el.com" <maciej.fijalkowski@...el.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "toke@...hat.com" <toke@...hat.com>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "aelior@...vell.com" <aelior@...vell.com>,
        "manishc@...vell.com" <manishc@...vell.com>,
        "horatiu.vultur@...rochip.com" <horatiu.vultur@...rochip.com>,
        "UNGLinuxDriver@...rochip.com" <UNGLinuxDriver@...rochip.com>,
        "mst@...hat.com" <mst@...hat.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        Ioana Ciornei <ioana.ciornei@....com>,
        Madalin Bucur <madalin.bucur@....com>
CC:     "bpf@...r.kernel.org" <bpf@...r.kernel.org>
Subject: RE: [PATCH net v2 4/5] dpaa_eth: execute xdp_do_flush() before
 napi_complete_done()

> -----Original Message-----
> From: Magnus Karlsson <magnus.karlsson@...il.com>
> Sent: Wednesday, January 25, 2023 9:49
> To: magnus.karlsson@...el.com; bjorn@...nel.org; ast@...nel.org;
> daniel@...earbox.net; netdev@...r.kernel.org;
> jonathan.lemon@...il.com; maciej.fijalkowski@...el.com;
> kuba@...nel.org; toke@...hat.com; pabeni@...hat.com;
> davem@...emloft.net; aelior@...vell.com; manishc@...vell.com;
> horatiu.vultur@...rochip.com; UNGLinuxDriver@...rochip.com;
> mst@...hat.com; jasowang@...hat.com; Ioana Ciornei
> <ioana.ciornei@....com>; Madalin Bucur <madalin.bucur@....com>
> Cc: bpf@...r.kernel.org
> Subject: [PATCH net v2 4/5] dpaa_eth: execute xdp_do_flush() before
> napi_complete_done()
> 
> From: Magnus Karlsson <magnus.karlsson@...el.com>
> 
> Make sure that xdp_do_flush() is always executed before
> napi_complete_done(). This is important for two reasons. First, a
> redirect to an XSKMAP assumes that a call to xdp_do_redirect() from
> napi context X on CPU Y will be followed by a xdp_do_flush() from the
> same napi context and CPU. This is not guaranteed if the
> napi_complete_done() is executed before xdp_do_flush(), as it tells
> the napi logic that it is fine to schedule napi context X on another
> CPU. Details from a production system triggering this bug using the
> veth driver can be found following the first link below.
> 
> The second reason is that the XDP_REDIRECT logic in itself relies on
> being inside a single NAPI instance through to the xdp_do_flush() call
> for RCU protection of all in-kernel data structures. Details can be
> found in the second link below.
> 
> Fixes: a1e031ffb422 ("dpaa_eth: add XDP_REDIRECT support")
> Signed-off-by: Magnus Karlsson <magnus.karlsson@...el.com>
> Acked-by: Toke Høiland-Jørgensen <toke@...hat.com>
> Link: https://lore.kernel.org/r/20221220185903.1105011-1-sbohrer@cloudflare.com
> Link: https://lore.kernel.org/all/20210624160609.292325-1-toke@redhat.com/
> ---

Acked-by: Camelia Groza <camelia.groza@....com>

Thanks!

>  drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> index 3f8032947d86..027fff9f7db0 100644
> --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> @@ -2410,6 +2410,9 @@ static int dpaa_eth_poll(struct napi_struct *napi, int
> budget)
> 
>  	cleaned = qman_p_poll_dqrr(np->p, budget);
> 
> +	if (np->xdp_act & XDP_REDIRECT)
> +		xdp_do_flush();
> +
>  	if (cleaned < budget) {
>  		napi_complete_done(napi, cleaned);
>  		qman_p_irqsource_add(np->p, QM_PIRQ_DQRI);
> @@ -2417,9 +2420,6 @@ static int dpaa_eth_poll(struct napi_struct *napi, int
> budget)
>  		qman_p_irqsource_add(np->p, QM_PIRQ_DQRI);
>  	}
> 
> -	if (np->xdp_act & XDP_REDIRECT)
> -		xdp_do_flush();
> -
>  	return cleaned;
>  }
> 
> --
> 2.34.1