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Message-ID: <20240517171254.1e316e69@kmaincent-XPS-13-7390>
Date: Fri, 17 May 2024 17:12:54 +0200
From: Kory Maincent <kory.maincent@...tlin.com>
To: Simon Horman <horms@...nel.org>
Cc: Florian Fainelli <florian.fainelli@...adcom.com>, Broadcom internal
kernel review list <bcm-kernel-feedback-list@...adcom.com>, Andrew Lunn
<andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>, Russell King
<linux@...linux.org.uk>, "David S. Miller" <davem@...emloft.net>, Eric
Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo
Abeni <pabeni@...hat.com>, Richard Cochran <richardcochran@...il.com>, Radu
Pirea <radu-nicolae.pirea@....nxp.com>, Jay Vosburgh
<j.vosburgh@...il.com>, Andy Gospodarek <andy@...yhouse.net>, Nicolas Ferre
<nicolas.ferre@...rochip.com>, Claudiu Beznea <claudiu.beznea@...on.dev>,
Willem de Bruijn <willemdebruijn.kernel@...il.com>, Jonathan Corbet
<corbet@....net>, Horatiu Vultur <horatiu.vultur@...rochip.com>,
UNGLinuxDriver@...rochip.com, Vladimir Oltean <vladimir.oltean@....com>,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, Maxime Chevallier
<maxime.chevallier@...tlin.com>, Rahul Rameshbabu <rrameshbabu@...dia.com>
Subject: Re: [PATCH net-next v12 12/13] net: ethtool: tsinfo: Add support
for hwtstamp provider and get/set hwtstamp config
On Sat, 4 May 2024 11:33:05 +0100
Simon Horman <horms@...nel.org> wrote:
> Hi Kory,
>
> A few lines beyond this hunk, within the "if (hwtstamp)" block,
> is the following:
>
> cfg->qualifier = dev->hwtstamp->qualifier;
>
> Now that dev->hwtstamp is managed using RCU, I don't think it is correct
> to dereference it directly like this. Rather, the hwtstamp local variable,
> which has rcu_dereference'd this pointer should be used:
>
> cfg->qualifier = hwtstamp->qualifier;
>
> Flagged by Sparse.
Yes indeed, thanks for the report.
>
> ...
>
> > diff --git a/net/ethtool/tsinfo.c b/net/ethtool/tsinfo.c
>
> ...
>
> > +static int ethnl_tsinfo_dump_one_dev(struct sk_buff *skb, struct
> > net_device *dev,
> > + struct netlink_callback *cb)
> > +{
> > + struct ethnl_tsinfo_dump_ctx *ctx = (void *)cb->ctx;
> > + struct ptp_clock *ptp;
> > + int ret;
> > +
> > + netdev_for_each_ptp_clock_start(dev, ctx->pos_phcindex, ptp,
> > + ctx->pos_phcindex) {
> > + ret = ethnl_tsinfo_dump_one_ptp(skb, dev, cb, ptp);
> > + if (ret < 0 && ret != -EOPNOTSUPP)
> > + break;
> > + ctx->pos_phcqualifier =
> > HWTSTAMP_PROVIDER_QUALIFIER_PRECISE;
> > + }
> > +
> > + return ret;
>
> Perhaps it is not possible, but if the loop iterates zero times then
> ret will be used uninitialised here.
Yes thanks!
Regards,
--
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com
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