From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: xen-devel@lists.xenproject.org, qemu-devel@nongnu.org, JBeulich@suse.com
Subject: Re: [PATCH v1 03/10] xen/pt: Check if reg->init function sets the 'data' past the reg->size
Date: Fri, 14 Aug 2015 16:42:38 -0400 [thread overview]
Message-ID: <20150814204238.GA21854__42760.7814468958$1439585066$gmane$org@l.oracle.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1507171700570.17378@kaball.uk.xensource.com>
On Fri, Jul 17, 2015 at 05:03:44PM +0100, Stefano Stabellini wrote:
> 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 <konrad.wilk@oracle.com>
> > ---
> > 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)?
I couldnt' figure out how to make that work nicely.
The QEMU_BUILD_BUG_ON look to be build time - not run-time.
Which means that doing:
for (i = 0; i < grp_entries; i++)
{
entries = grp_entries[i]...
for (j = 0; j < entries; j++)
QEMU_BUILD_BUG_ON(entries[j].init_val & ~size_mask)
}
is not something I can image the compiler working with?
>
>
> > /* 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
> >
next prev parent reply other threads:[~2015-08-14 20:42 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1435866681-18468-1-git-send-email-konrad.wilk@oracle.com>
2015-07-02 19:51 ` [PATCH v1 01/10] xen/pt: Use xen_host_pci_get_[byte|word] instead of dev.config Konrad Rzeszutek Wilk
2015-07-02 19:51 ` [PATCH v1 02/10] xen/pt: Sync up the dev.config and data values Konrad Rzeszutek Wilk
2015-07-17 15:54 ` Stefano Stabellini
2015-07-02 19:51 ` [PATCH v1 03/10] xen/pt: Check if reg->init function sets the 'data' past the reg->size Konrad Rzeszutek Wilk
2015-07-17 16:03 ` Stefano Stabellini
[not found] ` <alpine.DEB.2.02.1507171700570.17378@kaball.uk.xensource.com>
2015-07-17 16:47 ` Konrad Rzeszutek Wilk
2015-08-14 20:42 ` Konrad Rzeszutek Wilk [this message]
2015-07-02 19:51 ` [PATCH v1 04/10] xen/pt: Use xen_host_pci_get_[byte, word, long] instead of xen_host_pci_get_long Konrad Rzeszutek Wilk
2015-07-17 15:59 ` Stefano Stabellini
2015-07-02 19:51 ` [PATCH v1 05/10] xen/pt: Remove XenPTReg->data field Konrad Rzeszutek Wilk
2015-07-17 16:30 ` Stefano Stabellini
[not found] ` <alpine.DEB.2.02.1507171725050.17378@kaball.uk.xensource.com>
2015-07-17 16:48 ` Konrad Rzeszutek Wilk
2015-07-02 19:51 ` [PATCH v1 06/10] xen/pt: Log xen_host_pci_get in two init functions Konrad Rzeszutek Wilk
2015-07-02 19:51 ` [PATCH v1 07/10] xen/pt: Log xen_host_pci_get/set errors in MSI code Konrad Rzeszutek Wilk
2015-07-02 19:51 ` [PATCH v1 08/10] xen/pt: Make xen_pt_unregister_device idempotent Konrad Rzeszutek Wilk
2015-07-02 19:51 ` [PATCH v1 09/10] xen/pt: Move bulk of xen_pt_unregister_device in its own routine Konrad Rzeszutek Wilk
2015-07-02 19:51 ` [PATCH v1 10/10] xen/pt: Check for return values for xen_host_pci_[get|set] in init Konrad Rzeszutek Wilk
2015-07-08 19:19 ` [PATCH] Follow-on to Remove XenPTReg->data and use dev.config for guest configuration values Konrad Rzeszutek Wilk
[not found] ` <1436383152-18033-1-git-send-email-konrad.wilk@oracle.com>
2015-07-08 19:19 ` [PATCH] xen/pt: Don't slurp wholesale the PCI configuration registers Konrad Rzeszutek Wilk
[not found] ` <1436383152-18033-2-git-send-email-konrad.wilk@oracle.com>
2015-07-17 16:34 ` Stefano Stabellini
[not found] ` <1435866681-18468-2-git-send-email-konrad.wilk@oracle.com>
2015-07-17 15:43 ` [PATCH v1 01/10] xen/pt: Use xen_host_pci_get_[byte|word] instead of dev.config Stefano Stabellini
[not found] ` <1435866681-18468-9-git-send-email-konrad.wilk@oracle.com>
2015-07-17 16:14 ` [PATCH v1 08/10] xen/pt: Make xen_pt_unregister_device idempotent Stefano Stabellini
[not found] ` <alpine.DEB.2.02.1507171710110.17378@kaball.uk.xensource.com>
2015-08-14 20:20 ` Konrad Rzeszutek Wilk
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