linux-kernel - Re: [PATCH v2 2/2] usb: dwc3: Prevent cleanup cancelled requests at the same time.

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Date:   Mon, 14 Feb 2022 12:30:32 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Daehwan Jung <dh10.jung@...sung.com>
Cc:     Felipe Balbi <balbi@...nel.org>, linux-usb@...r.kernel.org,
        open list <linux-kernel@...r.kernel.org>,
        quic_wcheng@...cinc.com, quic_jackp@...cinc.com,
        Thinh.Nguyen@...opsys.com
Subject: Re: [PATCH v2 2/2] usb: dwc3: Prevent cleanup cancelled requests at
 the same time.

On Mon, Feb 14, 2022 at 08:08:53PM +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)
> 
> [2: MtpServer: 5032] dwc3 10b00000.dwc3: request cancelled
> 						with wrong reason:5
> [2: MtpServer: 5032] list_del corruption,
> 		ffffff88b6963968->next is LIST_POISON1 (dead000000000100)
> 
> Signed-off-by: Daehwan Jung <dh10.jung@...sung.com>
> ---
>  drivers/usb/dwc3/gadget.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)

What commit id does this fix?

thanks,

greg k-h