From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51718) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1adwn3-0005T8-L7 for qemu-devel@nongnu.org; Thu, 10 Mar 2016 04:21:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1adwmy-000726-Li for qemu-devel@nongnu.org; Thu, 10 Mar 2016 04:21:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42204) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1adwmy-000722-GV for qemu-devel@nongnu.org; Thu, 10 Mar 2016 04:21:48 -0500 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (Postfix) with ESMTPS id 70E8670A9B for ; Thu, 10 Mar 2016 09:21:47 +0000 (UTC) Message-ID: <1457601705.6405.48.camel@redhat.com> From: Gerd Hoffmann Date: Thu, 10 Mar 2016 10:21:45 +0100 In-Reply-To: <20160310075612.GA30354@pxdev.xzpeter.org> References: <1457575914-15581-1-git-send-email-peterx@redhat.com> <1457595253.6405.3.camel@redhat.com> <20160310075612.GA30354@pxdev.xzpeter.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH] usb: fix unbounded stack warning for xhci_dma_write_u32s List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Xu Cc: pbonzini@redhat.com, qemu-devel@nongnu.org On Do, 2016-03-10 at 15:56 +0800, Peter Xu wrote: > On Thu, Mar 10, 2016 at 08:34:13AM +0100, Gerd Hoffmann wrote: > > On Do, 2016-03-10 at 10:11 +0800, Peter Xu wrote: > > > Signed-off-by: Peter Xu > > > --- > > > hw/usb/hcd-xhci.c | 6 ++++-- > > > 1 file changed, 4 insertions(+), 2 deletions(-) > > >=20 > > > diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c > > > index 44b6f8c..d15918f 100644 > > > --- a/hw/usb/hcd-xhci.c > > > +++ b/hw/usb/hcd-xhci.c > > > @@ -698,11 +698,13 @@ static inline void xhci_dma_write_u32s(XHCIStat= e *xhci, dma_addr_t addr, > > > uint32_t *buf, size_t len) > > > { > > > int i; > > > - uint32_t tmp[len / sizeof(uint32_t)]; > > > + uint32_t tmp[12]; > >=20 > > Where does the 12 come from? >=20 > As mentioned in previous thread, because all the callers of > xhci_dma_write_u32s() are using const size in "len". The maximum > currently is 5 * sizeof(uint32_t) =3D 20 bytes Can you note that in the commit message please? > . Here I choose number > bigger than 5 should work for now. Why bigger? 5 should do just fine then, and the assert added should make sure we'll notice if this needs an update due to code changes elsewhere. thanks, Gerd