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Mon, 11 Jan 2021 06:31:29 -0800 (PST) Date: Mon, 11 Jan 2021 21:31:20 +0700 From: Bui Quang Minh To: Oliver Neukum Cc: linux-usb@vger.kernel.org, a.darwish@linutronix.de, bigeasy@linutronix.de, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, stern@rowland.harvard.edu, syzkaller-bugs@googlegroups.com, tglx@linutronix.de Subject: Re: [PATCH v2] can: mcba_usb: Fix memory leak when cancelling urb Message-ID: <20210111143120.GA2769@minh> References: <20210111104927.2561-1-minhquangbui99@gmail.com> <7d6dc09fedc84f9fce942d85c34d5cd41931bbf6.camel@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7d6dc09fedc84f9fce942d85c34d5cd41931bbf6.camel@suse.de> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 11, 2021 at 01:00:31PM +0100, Oliver Neukum wrote: > Am Montag, den 11.01.2021, 10:49 +0000 schrieb Bui Quang Minh: > > In mcba_usb_read_bulk_callback(), when we don't resubmit or fails to > > resubmit the urb, we need to deallocate the transfer buffer that is > > allocated in mcba_usb_start(). > > > > Reported-by: syzbot+57281c762a3922e14dfe@syzkaller.appspotmail.com > > Signed-off-by: Bui Quang Minh > > --- > > v1: add memory leak fix when not resubmitting urb > > v2: add memory leak fix when failing to resubmit urb > > > > drivers/net/can/usb/mcba_usb.c | 11 ++++++++--- > > 1 file changed, 8 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/net/can/usb/mcba_usb.c b/drivers/net/can/usb/mcba_usb.c > > index df54eb7d4b36..30236e640116 100644 > > --- a/drivers/net/can/usb/mcba_usb.c > > +++ b/drivers/net/can/usb/mcba_usb.c > > @@ -584,6 +584,8 @@ static void mcba_usb_read_bulk_callback(struct urb *urb) > > case -EPIPE: > > case -EPROTO: > > case -ESHUTDOWN: > > + usb_free_coherent(urb->dev, urb->transfer_buffer_length, > > + urb->transfer_buffer, urb->transfer_dma); > > return; > > > > Can you call usb_free_coherent() in what can be hard IRQ context? You are right, I digged in the code and saw some comments that on some architectures, usb_free_coherent() cannot be called in hard IRQ context. I see the usb_free_coherent() is called in write_bulk_callback too. I will send a patch that uses usb_anchor to keep track of these urbs and cleanup the transfer buffer later in disconnect(). Thank you for your review, Quang Minh.