netdev - Re: [PATCH net-next] net: ethtool: phy: Distinguish whether dev is got by phy start or doit

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Message-ID: <20240913135145.2c9ac50c@fedora.home>
Date: Fri, 13 Sep 2024 13:51:45 +0200
From: Maxime Chevallier <maxime.chevallier@...tlin.com>
To: Lizhi Xu <lizhi.xu@...driver.com>
Cc: <syzbot+e9ed4e4368d450c8f9db@...kaller.appspotmail.com>,
 <christophe.leroy@...roup.eu>, <davem@...emloft.net>,
 <edumazet@...gle.com>, <kuba@...nel.org>, <linux-kernel@...r.kernel.org>,
 <netdev@...r.kernel.org>, <pabeni@...hat.com>,
 <syzkaller-bugs@...glegroups.com>
Subject: Re: [PATCH net-next] net: ethtool: phy: Distinguish whether dev is
 got by phy start or doit

Hi,

On Fri, 13 Sep 2024 16:07:13 +0800
Lizhi Xu <lizhi.xu@...driver.com> wrote:

> Syzbot reported a refcount bug in ethnl_phy_done.
> This is because when executing ethnl_phy_done, it does not know who obtained
> the dev(it can be got by ethnl_phy_doit or ethnl_phy_start) and directly
> executes ethnl_parse_header_dev_put as long as the dev is not NULL.
> Add dev_start_doit to the structure phy_req_info to distinguish who obtains dev.
> 
> Fixes: 17194be4c8e1 ("net: ethtool: Introduce a command to list PHYs on an interface")
> Reported-and-tested-by: syzbot+e9ed4e4368d450c8f9db@...kaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=e9ed4e4368d450c8f9db
> Signed-off-by: Lizhi Xu <lizhi.xu@...driver.com>

Thanks for addressing this, however I've already sent a first fix for
this [1] yesterday, followed-up by a second one [2] with another
approach following the reviews.

[1] : https://lore.kernel.org/netdev/20240913091404.3d4a9d19@fedora.home/T/#m4777416dbe26bf97b3a0a323fc71a93b40e0f7fb
[2] : https://lore.kernel.org/netdev/20240913100515.167341-1-maxime.chevallier@bootlin.com/T/#u

Best regards,

Maxime