From: Venu Byravarasu <vbyravarasu@nvidia.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1] usb: host: Fix possible kernel crash
Date: Wed, 11 Jul 2012 12:34:08 +0530 [thread overview]
Message-ID: <4FFD2568.6070404@nvidia.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1207101108060.1308-100000@iolanthe.rowland.org>
On Tuesday 10 July 2012 08:39 PM, Alan Stern wrote:
> On Tue, 10 Jul 2012, Venu Byravarasu wrote:
>
>> Thanks Alan for your comments.
>>
>> On Monday 09 July 2012 08:04 PM, Alan Stern wrote:
>>> On Mon, 9 Jul 2012, Venu Byravarasu wrote:
>>>
>>>> In functions itd_complete & sitd_complete, a pointer
>>>> by name stream may get dereferenced after freeing it, when
>>>> iso_stream_put is called with stream->refcount = 2.
>>> I don't understand the problem. Did you actually see this happen or is
>>> it only theoretical?
>> Yes it is a theoretical problem, as complained by Coverity.
>> As per the logic you explained above, this change is not needed.
>> However coverity was complaining as below:
>>
>> /kernel/drivers/usb/host/ehci-sched.c 1777 USE_AFTER_FREE Dereferencing
>> freed pointer "stream"
>>
>> Hence to pacify coverity, this change is done.
>> Please let me know if you see any other better way to handle it.
> This seems to be a false positive from Coverity.
>
> In any case, I'm about to submit some patches which get rid of the
> reference counting entirely. So let's not worry about this.
>
> Alan Stern
>
Thanks Alan for taking care of it, in your future patch.
prev parent reply other threads:[~2012-07-11 7:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-09 10:46 [PATCH v1] usb: host: Fix possible kernel crash Venu Byravarasu
2012-07-09 14:34 ` Alan Stern
2012-07-10 4:26 ` Venu Byravarasu
2012-07-10 14:45 ` gregkh
2012-07-10 16:35 ` Scan Subscription
2012-07-11 7:03 ` Venu Byravarasu
2012-07-11 7:05 ` Venu Byravarasu
2012-07-10 15:09 ` Alan Stern
2012-07-11 7:04 ` Venu Byravarasu [this message]
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