netdev - Re: [PATCH net 1/7] bnx2x: prevent crash when accessing PTP with interface down

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Message-ID: <1af37eff-26dd-8f3f-5f2e-ec2ab39055a3@redhat.com>
Date:   Mon, 6 Mar 2017 15:04:22 +0100
From:   Michal Schmidt <mschmidt@...hat.com>
To:     "Mintz, Yuval" <Yuval.Mintz@...ium.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Cc:     "Elior, Ariel" <Ariel.Elior@...ium.com>
Subject: Re: [PATCH net 1/7] bnx2x: prevent crash when accessing PTP with
 interface down

Dne 5.3.2017 v 10:43 Mintz, Yuval napsal(a):
>> It is possible to crash the kernel by accessing a PTP device while its
>> associated bnx2x interface is down. Before the interface is brought up, the
>> timecounter is not initialized, so accessing it results in NULL dereference.
>>
>> Fix it by checking if the interface is up.
>>
>> Use -ENETDOWN as the error code when the interface is down.
>>  -EFAULT in bnx2x_ptp_adjfreq() did not seem right.
>>
>> Tested using phc_ctl get/set/adj/freq commands.
>>
>> Signed-off-by: Michal Schmidt <mschmidt@...hat.com>
>
> While I have no objections to the patch contents, does it even make
> sense to try adjusting frequencies on a DOWNed interface?
> Wouldn't it make more sense checking this in the calling context
> Instead?

The caller does not know. A PTP device is not necessarily associated 
with a net device.

Michal