linux-kernel - Re: [PATCH] usb: cdnsp: Fix a NULL pointer dereference in cdnsp_endpoint

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Date:   Wed, 1 Dec 2021 22:16:07 +0800
From:   Peter Chen <peter.chen@...nel.org>
To:     Pawel Laszczak <pawell@...ence.com>
Cc:     Zhou Qingyang <zhou1615@....edu>, "kjlu@....edu" <kjlu@....edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: cdnsp: Fix a NULL pointer dereference in
 cdnsp_endpoint_init()

On 21-12-01 07:39:05, Pawel Laszczak wrote:
> Only fixed Peter Chen address email:
> peter.chen@....com  doesn't exist, should be peter.chen@...nel.org
> 
> >-----Original Message-----
> >From: Pawel Laszczak
> >Sent: Wednesday, December 1, 2021 8:28 AM
> >To: Zhou Qingyang <zhou1615@....edu>
> >Cc: kjlu@....edu; Greg Kroah-Hartman <gregkh@...uxfoundation.org>; Peter Chen <peter.chen@....com>; linux-
> >usb@...r.kernel.org; linux-kernel@...r.kernel.org
> >Subject: RE: [PATCH] usb: cdnsp: Fix a NULL pointer dereference in cdnsp_endpoint_init()
> >
> >>
> >>In cdnsp_endpoint_init(), cdnsp_ring_alloc() is assigned to pep->ring
> >>and there is a dereference of it in cdnsp_endpoint_init(), which could
> >>lead to a NULL pointer dereference on failure of cdnsp_ring_alloc().
> >>
> >>Fix this bug by adding a check of pep->ring.
> >>
> >>This bug was found by a static analyzer. The analysis employs
> >>differential checking to identify inconsistent security operations
> >>(e.g., checks or kfrees) between two code paths and confirms that the
> >>inconsistent operations are not recovered in the current function or
> >>the callers, so they constitute bugs.
> >>
> >>Note that, as a bug found by static analysis, it can be a false
> >>positive or hard to trigger. Multiple researchers have cross-reviewed
> >>the bug.
> >>
> >>Builds with CONFIG_USB_CDNSP_GADGET=y show no new warnings,
> >>and our static analyzer no longer warns about this code.
> >>
> >>Fixes: 3d82904559f4 ("usb: cdnsp: cdns3 Add main part of Cadence USBSSP DRD Driver")
> >>Signed-off-by: Zhou Qingyang <zhou1615@....edu>
> >>---
> >> drivers/usb/cdns3/cdnsp-mem.c | 3 +++
> >> 1 file changed, 3 insertions(+)
> >>
> >>diff --git a/drivers/usb/cdns3/cdnsp-mem.c b/drivers/usb/cdns3/cdnsp-mem.c
> >>index ad9aee3f1e39..97866bfb2da9 100644
> >>--- a/drivers/usb/cdns3/cdnsp-mem.c
> >>+++ b/drivers/usb/cdns3/cdnsp-mem.c
> >>@@ -987,6 +987,9 @@ int cdnsp_endpoint_init(struct cdnsp_device *pdev,
> >>
> >> 	/* Set up the endpoint ring. */
> >> 	pep->ring = cdnsp_ring_alloc(pdev, 2, ring_type, max_packet, mem_flags);
> >>+	if (!pep->ring)
> >>+		return -ENOMEM;
> >>+
> >> 	pep->skip = false;
> >>
> >> 	/* Fill the endpoint context */
> >>--
> >>2.25.1
> >
> >
> >Acked-by: Pawel Laszczak <pawell@...ence.com>

Acked-by: Peter Chen <peter.chen@...nel.org>

> >
> >--
> >
> >Thanks,
> >Pawel Laszczak

-- 

Thanks,
Peter Chen