| Message ID | 1435866681-18468-4-git-send-email-konrad.wilk@oracle.com |
|---|---|
| State | New |
| Headers | show |
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)? > /* 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 >
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)? Duh. Yes :-) > > > > /* 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 > >
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 > >
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; + } /* 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;
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(-)