netdev - Re: [PATCH 1/2 net] ptp: fix error codes in ptp_clock

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Message-ID: <20170710093457.xzc5i5zg34z3thjr@localhost.localdomain>
Date:   Mon, 10 Jul 2017 11:34:57 +0200
From:   Richard Cochran <richardcochran@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Ganesh Goudar <ganeshgr@...lsio.com>,
        Atul Gupta <atul.gupta@...lsio.com>, netdev@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 1/2 net] ptp: fix error codes in ptp_clock_register()

On Mon, Jul 10, 2017 at 10:11:37AM +0300, Dan Carpenter wrote:
> The ptp_clock_register() function returns NULL when it's #ifdefed out
> because CONFIG_PTP_1588_CLOCK is disabled.  Otherwise, it's intended to
> return error pointers.  Unfortunately, there are a couple paths where we
> forget to set the error code.  It means that we could result in NULL
> pointer dereferences in the callers.

Actually, this description is bogus.  Callers will not dereference
NULL, because they are required to check the returned pointer:

/**
 * ptp_clock_register() - register a PTP hardware clock driver
 *
 * @info:   Structure describing the new clock.
 * @parent: Pointer to the parent device of the new clock.
 *
 * Returns a valid pointer on success or PTR_ERR on failure.  If PHC
 * support is missing at the configuration level, this function
 * returns NULL, and drivers are expected to gracefully handle that
 * case separately.
 */

Thanks,
Richard