linux-kernel - Re: [PATCH] ptp: free ptp device pin descriptors properly

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Date:   Mon, 13 Jan 2020 20:26:16 -0800
From:   Richard Cochran <richardcochran@...il.com>
To:     Vladis Dronov <vdronov@...hat.com>
Cc:     Antti Laakso <antti.laakso@...el.com>, netdev@...r.kernel.org,
        sjohnsto@...hat.com, vlovejoy@...hat.com,
        linux-kernel@...r.kernel.org, davem@...emloft.net,
        artem.bityutskiy@...el.com
Subject: Re: [PATCH] ptp: free ptp device pin descriptors properly

On Mon, Jan 13, 2020 at 02:00:09PM +0100, Vladis Dronov wrote:
> There is a bug in ptp_clock_unregister(), where ptp_cleanup_pin_groups()
> first frees ptp->pin_{,dev_}attr, but then posix_clock_unregister() needs
> them to destroy a related sysfs device.
> 
> These functions can not be just swapped, as posix_clock_unregister() frees
> ptp which is needed in the ptp_cleanup_pin_groups(). Fix this by calling
> ptp_cleanup_pin_groups() in ptp_clock_release(), right before ptp is freed.
> 
> This makes this patch fix an UAF bug in a patch which fixes an UAF bug.
> 
> Reported-by: Antti Laakso <antti.laakso@...el.com>
> Fixes: a33121e5487b ("ptp: fix the race between the release of ptp_clock and cdev")
> Link: https://lore.kernel.org/netdev/3d2bd09735dbdaf003585ca376b7c1e5b69a19bd.camel@intel.com/
> Signed-off-by: Vladis Dronov <vdronov@...hat.com>

Acked-by: Richard Cochran <richardcochran@...il.com>