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Sat, 01 Feb 2020 03:20:42 -0800 Received: from MTKMBS07N2.mediatek.inc (172.21.101.141) by MTKMBS62N1.mediatek.inc (172.29.193.41) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Sat, 1 Feb 2020 03:21:09 -0800 Received: from MTKCAS06.mediatek.inc (172.21.101.30) by mtkmbs07n2.mediatek.inc (172.21.101.141) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Sat, 1 Feb 2020 19:20:01 +0800 Received: from [172.21.77.33] (172.21.77.33) by MTKCAS06.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Sat, 1 Feb 2020 19:18:14 +0800 Message-ID: <1580556039.10835.3.camel@mtkswgap22> Subject: Re: [PATCH] xhci-mtk: Fix NULL pointer dereference with xhci_irq() for shared_hcd From: Macpaul Lin To: Mathias Nyman Date: Sat, 1 Feb 2020 19:20:39 +0800 In-Reply-To: <08f69bab-2ada-d6ab-7bf7-d960e9f148a0@linux.intel.com> References: <1579246910-22736-1-git-send-email-macpaul.lin@mediatek.com> <08f69bab-2ada-d6ab-7bf7-d960e9f148a0@linux.intel.com> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200201_032051_793046_37F5A16C X-CRM114-Status: GOOD ( 20.18 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sriharsha Allenki , Mediatek WSD Upstream , Mathias Nyman , Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Chunfeng Yun , linux-mediatek@lists.infradead.org, Matthias Brugger , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 2020-01-31 at 16:50 +0200, Mathias Nyman wrote: > On 17.1.2020 9.41, Macpaul Lin wrote: > > According to NULL pointer fix: https://tinyurl.com/uqft5ra > > xhci: Fix NULL pointer dereference with xhci_irq() for shared_hcd > > The similar issue has also been found in QC activities in Mediatek. > > > > Here quote the description from the referenced patch as follows. > > "Commit ("f068090426ea xhci: Fix leaking USB3 shared_hcd > > at xhci removal") sets xhci_shared_hcd to NULL without > > stopping xhci host. This results into a race condition > > where shared_hcd (super speed roothub) related interrupts > > are being handled with xhci_irq happens when the > > xhci_plat_remove is called and shared_hcd is set to NULL. > > Fix this by setting the shared_hcd to NULL only after the > > controller is halted and no interrupts are generated." > > > > Signed-off-by: Sriharsha Allenki > > Signed-off-by: Macpaul Lin > > --- > > drivers/usb/host/xhci-mtk.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/usb/host/xhci-mtk.c b/drivers/usb/host/xhci-mtk.c > > index b18a6baef204..c227c67f5dc5 100644 > > --- a/drivers/usb/host/xhci-mtk.c > > +++ b/drivers/usb/host/xhci-mtk.c > > @@ -593,11 +593,11 @@ static int xhci_mtk_remove(struct platform_device *dev) > > struct usb_hcd *shared_hcd = xhci->shared_hcd; > > > > usb_remove_hcd(shared_hcd); > > - xhci->shared_hcd = NULL; > > device_init_wakeup(&dev->dev, false); > > > > usb_remove_hcd(hcd); > > usb_put_hcd(shared_hcd); > > + xhci->shared_hcd = NULL; > > usb_put_hcd(hcd); > > xhci_mtk_sch_exit(mtk); > > xhci_mtk_clks_disable(mtk); > > > > Could you share details of the NULL pointer dereference, (backtrace). This bug was found by our QA staff while doing 500 times plug-in and plug-out devices. The backtrace I have was recorded by QA and I didn't reproduce this issue on my own environment. However, after applied this patch the issue seems resolve. Here is the backtrace: Exception Class: Kernel (KE) PC is at [] xhci_irq+0x728/0x2364 LR is at [] xhci_irq+0x2f0/0x2364 Current Executing Process: [iptables, 859][netdagent, 770] Backtrace: [] __atomic_notifier_call_chain+0xa8/0x130 [] notify_die+0x84/0xac [] die+0x1d8/0x3b8 [] __do_kernel_fault+0x178/0x188 [] do_page_fault+0x44/0x3b0 [] do_translation_fault+0x44/0x98 [] do_mem_abort+0x4c/0x128 [] el1_da+0x24/0x3c [] xhci_irq+0x728/0x2364 [] usb_hcd_irq+0x2c/0x44 [] __handle_irq_event_percpu+0x26c/0x4a4 [] handle_irq_event+0x5c/0xd0 [] handle_fasteoi_irq+0x10c/0x1e0 [] __handle_domain_irq+0x32c/0x738 [] gic_handle_irq+0x174/0x1c4 [] el0_irq_naked+0x50/0x5c [] 0xffffffffffffffff > The USB3 hcd is already removed when xhci->shared_hcd is set to NULL. > We might want to add some checks to make sure we are not using the removed > hcd anymore in that codepath anymore. > > -Mathias Thanks, Macpaul Lin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel