From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefano Stabellini Subject: Re: [PATCH v1 03/10] xen/pt: Check if reg->init function sets the 'data' past the reg->size Date: Fri, 17 Jul 2015 17:03:44 +0100 Message-ID: References: <1435866681-18468-1-git-send-email-konrad.wilk@oracle.com> <1435866681-18468-4-git-send-email-konrad.wilk@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1ZG8Ae-000300-Je for xen-devel@lists.xenproject.org; Fri, 17 Jul 2015 16:07:32 +0000 In-Reply-To: <1435866681-18468-4-git-send-email-konrad.wilk@oracle.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Konrad Rzeszutek Wilk Cc: xen-devel@lists.xenproject.org, qemu-devel@nongnu.org, JBeulich@suse.com, stefano.stabellini@eu.citrix.com List-Id: xen-devel@lists.xenproject.org On Thu, 2 Jul 2015, Konrad Rzeszutek Wilk wrote: > It should never happen, but in case it does (an developer adds > a new register and the 'init_val' expands past the register > size) we want to report. The code will only write up to > reg->size so there is no runtime danger of the register spilling > across other ones - however to catch this sort of thing > we still return an error. > > Signed-off-by: Konrad Rzeszutek Wilk > --- > hw/xen/xen_pt_config_init.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/hw/xen/xen_pt_config_init.c b/hw/xen/xen_pt_config_init.c > index 3938afd..09309ba 100644 > --- a/hw/xen/xen_pt_config_init.c > +++ b/hw/xen/xen_pt_config_init.c > @@ -1904,9 +1904,15 @@ static int xen_pt_config_reg_init(XenPCIPassthroughState *s, > } else > val = data; > > + if (val & ~size_mask) { > + XEN_PT_ERR(&s->dev,"Offset 0x%04x:0x%04x expands past register size(%d)!\n", > + offset, val, reg->size); > + g_free(reg_entry); > + return -ENXIO; > + } If we worry about changes to init_val, wouldn't it be better to add QEMU_BUILD_BUG_ON(data & ~size_mask)? > /* This could be just pci_set_long as we don't modify the bits > - * past reg->size, but in case this routine is run in parallel > - * we do not want to over-write other registers. */ > + * past reg->size, but in case this routine is run in parallel or the > + * init value is larger, we do not want to over-write registers. */ > switch (reg->size) { > case 1: pci_set_byte(s->dev.config + offset, (uint8_t)val); break; > case 2: pci_set_word(s->dev.config + offset, (uint16_t)val); break; > -- > 2.1.0 >