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Date:   Mon, 21 Feb 2022 17:28:11 +0900
From:   Jung Daehwan <dh10.jung@samsung.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Felipe Balbi <balbi@kernel.org>,
        Muchun Song <songmuchun@bytedance.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        linux-usb@vger.kernel.org, open list <linux-kernel@vger.kernel.org>
Subject: Re: usb: gadget: function: add spinlock for rndis response list
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On Fri, Feb 18, 2022 at 08:57:45AM +0100, Greg Kroah-Hartman wrote:
> On Fri, Feb 18, 2022 at 02:29:55PM +0900, Daehwan Jung wrote:
> > There's no lock for rndis response list. It could cause list corruption
> > if two different list_add at the same time like below.
> > It's better to add in rndis_add_response / rndis_free_response
> > / rndis_get_next_response to prevent any race condition on response list.
> > 
> > [  361.894299] [1:   irq/191-dwc3:16979] list_add corruption.
> > next->prev should be prev (ffffff80651764d0),
> > but was ffffff883dc36f80. (next=ffffff80651764d0).
> > 
> > [  361.904380] [1:   irq/191-dwc3:16979] Call trace:
> > [  361.904391] [1:   irq/191-dwc3:16979]  __list_add_valid+0x74/0x90
> > [  361.904401] [1:   irq/191-dwc3:16979]  rndis_msg_parser+0x168/0x8c0
> > [  361.904409] [1:   irq/191-dwc3:16979]  rndis_command_complete+0x24/0x84
> > [  361.904417] [1:   irq/191-dwc3:16979]  usb_gadget_giveback_request+0x20/0xe4
> > [  361.904426] [1:   irq/191-dwc3:16979]  dwc3_gadget_giveback+0x44/0x60
> > [  361.904434] [1:   irq/191-dwc3:16979]  dwc3_ep0_complete_data+0x1e8/0x3a0
> > [  361.904442] [1:   irq/191-dwc3:16979]  dwc3_ep0_interrupt+0x29c/0x3dc
> > [  361.904450] [1:   irq/191-dwc3:16979]  dwc3_process_event_entry+0x78/0x6cc
> > [  361.904457] [1:   irq/191-dwc3:16979]  dwc3_process_event_buf+0xa0/0x1ec
> > [  361.904465] [1:   irq/191-dwc3:16979]  dwc3_thread_interrupt+0x34/0x5c
> > 
> > Fixes: f6281af9d62e ("usb: gadget: rndis: use list_for_each_entry_safe")
> > Signed-off-by: Daehwan Jung <dh10.jung@samsung.com>
> > ---
> >  drivers/usb/gadget/function/rndis.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> > 
> > diff --git a/drivers/usb/gadget/function/rndis.c b/drivers/usb/gadget/function/rndis.c
> > index b7ccf1803656..b4d58324e2d2 100644
> > --- a/drivers/usb/gadget/function/rndis.c
> > +++ b/drivers/usb/gadget/function/rndis.c
> > @@ -1011,16 +1011,21 @@ void rndis_add_hdr(struct sk_buff *skb)
> >  }
> >  EXPORT_SYMBOL_GPL(rndis_add_hdr);
> >  
> > +/* add spinlock to prevent race condition for rndis response list */
> > +static DEFINE_SPINLOCK(resp_lock);
> 
> Shouldn't this be one lock per rndis_params structure, and not a global
> one for the whole driver?
> 
I agree with your comment. I'm going to modify and push it again.
Thanks for the comment.

Best Regards,
Jung Daehwan

> thanks,
> 
> greg k-h
> 

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