From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cornelia Huck Subject: Re: [PATCH 1/1] vfio: ccw: fix bad ptr math for TIC cda translation Date: Thu, 20 Jul 2017 11:10:12 +0200 Message-ID: <20170720111012.73adf738@gondolin> References: <20170720031950.64438-1-bjsdjshi@linux.vnet.ibm.com> <20170720031950.64438-2-bjsdjshi@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-s390@vger.kernel.org, kvm@vger.kernel.org, borntraeger@de.ibm.com, "Jason J. Herne" To: Dong Jia Shi Return-path: Received: from mx1.redhat.com ([209.132.183.28]:48310 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934006AbdGTJKR (ORCPT ); Thu, 20 Jul 2017 05:10:17 -0400 In-Reply-To: <20170720031950.64438-2-bjsdjshi@linux.vnet.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, 20 Jul 2017 05:19:50 +0200 Dong Jia Shi wrote: > From: "Jason J. Herne" > > When we are translating channel data addresses from guest to host > address space for TIC instructions we are getting incorrect > addresses because of a pointer arithmetic error. Ah, so you saw actual failures? > > We currently calculate the offset of the TIC's cda from the start > of the channel program chain (ccw->cda - ccw_head). We then add > that to the address of the ccw chain in host memory (iter->ch_ccw). > The problem is that iter->ch_ccw is a poiner to struct ccw1 so > when we increment it we are actually incrementing by the size of > struct ccw1 which is 8 bytes. The intent was to increment by > n-bytes, not n*8. > > The fix: cast iter->ch_ccw to char* so it will be incremented by > n*1. > > Reviewed-by: Dong Jia Shi > Signed-off-by: Jason J. Herne Please add your s-o-b if you send out patches, otherwise I cannot apply them, sorry. > --- > drivers/s390/cio/vfio_ccw_cp.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c > index ba6ac83a6c25..5ccfdc80d0ec 100644 > --- a/drivers/s390/cio/vfio_ccw_cp.c > +++ b/drivers/s390/cio/vfio_ccw_cp.c > @@ -481,7 +481,7 @@ static int ccwchain_fetch_tic(struct ccwchain *chain, > ccw_tail = ccw_head + (iter->ch_len - 1) * sizeof(struct ccw1); > > if ((ccw_head <= ccw->cda) && (ccw->cda <= ccw_tail)) { > - ccw->cda = (__u32) (addr_t) (iter->ch_ccw + > + ccw->cda = (__u32) (addr_t) (((char *)iter->ch_ccw) + > (ccw->cda - ccw_head)); > return 0; > }