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Date:   Mon, 14 Feb 2022 19:46:50 +0900
From:   Jung Daehwan <dh10.jung@samsung.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Felipe Balbi <balbi@kernel.org>, linux-usb@vger.kernel.org,
        open list <linux-kernel@vger.kernel.org>,
        quic_wcheng@quicinc.com, quic_jackp@quicinc.com,
        Thinh.Nguyen@synopsys.com
Subject: Re: [PATCH v1 2/2] usb: dwc3: Prevent cleanup cancelled requests at
 the same time.
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On Mon, Feb 14, 2022 at 11:42:03AM +0100, Greg Kroah-Hartman wrote:
> On Mon, Feb 14, 2022 at 06:37:18PM +0900, Daehwan Jung wrote:
> > We added cleanup cancelled requests when ep cmd timeout on ep dequeue
> > because there's no complete interrupt then. But, we find out new case
> > that complete interrupt comes up later. list_for_each_entry_safe is
> > used when cleanup cancelled requests and it has vulnerabilty on multi-core
> > environment. dwc3_gadget_giveback unlocks dwc->lock temporarily and other
> > core(ISR) can get lock and try to cleanup them again. It could cause
> > list_del corruption and we use DWC3_EP_END_TRANSFER_PENDING to prevent it.
> > 
> > 1. MTP server cancels -> ep dequeue -> ep cmd timeout(END_TRANSFER)
> >    -> cleanup cancelled requests -> dwc3_gadget_giveback -> list_del -> release lock temporarily
> > 2. Complete with END_TRANSFER -> ISR(dwc3_gadget_endpoint_command_complete) gets lock
> >    -> cleanup cancelled requests -> dwc3_gadget_giveback -> list_del
> > 3. MTP server process gets lock again -> tries to access POISON list(list_del corruption)
> > 
> > [  205.014697] [2:      MtpServer: 5032] dwc3 10b00000.dwc3: request cancelled with wrong reason:5
> > [  205.014719] [2:      MtpServer: 5032] list_del corruption, ffffff88b6963968->next is LIST_POISON1 (dead000000000100)
> > 
> > Change-Id: I9df055c6c04855edd09e330300914454a6657a23
> > Signed-off-by: Daehwan Jung <dh10.jung@samsung.com>
> > 
> > Change-Id: If87c88c3bb4c17ea1a5bde2bfec1382769f7ecab
> > Signed-off-by: Daehwan Jung <dh10.jung@samsung.com>
> 
> Why did you sign off on this twice?
> 
> And did you run it through checkpatch.pl?  It would have reminded you
> that Change-Id: should not be on patches :(
> 
> Same for patch 1/1.
> 
> Please fix.
> 
> thanks,
> 
> greg k-h
> 

Dear greg,

I'm so sorry. It's my fault when getting patches from our system.
I'm going to fix and re-send it.

Best Regards,
Jung Daehwan

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