| Message ID | 20200603202251.1199170-2-ppandit@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | Ensure PCI configuration access is within bounds | expand |
On Thu, 4 Jun 2020, P J P wrote: > From: Prasad J Pandit <pjp@fedoraproject.org> > > While reading PCI configuration bytes, a guest may send an > address towards the end of the configuration space. It may lead > to an OOB access issue. Add check to ensure 'address + size' is > within PCI configuration space. > > Reported-by: Ren Ding <rding@gatech.edu> > Reported-by: Hanqing Zhao <hanqing@gatech.edu> > Reported-by: Yi Ren <c4tren@gmail.com> > Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> > --- > hw/display/ati.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > Update v2: add check to avoid OOB PCI configuration space access > -> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg00711.html > > diff --git a/hw/display/ati.c b/hw/display/ati.c > index bda4a2d816..6671959e5d 100644 > --- a/hw/display/ati.c > +++ b/hw/display/ati.c > @@ -384,7 +384,10 @@ static uint64_t ati_mm_read(void *opaque, hwaddr addr, unsigned int size) > val = s->regs.crtc_pitch; > break; > case 0xf00 ... 0xfff: > - val = pci_default_read_config(&s->dev, addr - 0xf00, size); > + addr = addr - 0xf00; I'd write this as addr -= 0xf00 but modifying addr here breaks the trace print out at end of function so better drop this line and do if (addr + size <= 0xfff) { instead. Or is that really (addr + size - 1 <= 0xfff) considering that reading the last byte with addr = 0xfff size = 1 should probably be valid. Regards, BALATON Zoltan > + if (addr + size <= 0xff) { > + val = pci_default_read_config(&s->dev, addr, size); > + } > break; > case CUR_OFFSET: > val = s->regs.cur_offset; >
Typo: s/ait/ati/ On Thu, Jun 04, 2020 at 01:52:50AM +0530, P J P wrote: > From: Prasad J Pandit <pjp@fedoraproject.org> > > While reading PCI configuration bytes, a guest may send an > address towards the end of the configuration space. It may lead > to an OOB access issue. Add check to ensure 'address + size' is > within PCI configuration space. Please include a CVE number for this security flaw if there is one. > > Reported-by: Ren Ding <rding@gatech.edu> > Reported-by: Hanqing Zhao <hanqing@gatech.edu> > Reported-by: Yi Ren <c4tren@gmail.com> > Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> > --- > hw/display/ati.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > Update v2: add check to avoid OOB PCI configuration space access > -> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg00711.html > > diff --git a/hw/display/ati.c b/hw/display/ati.c > index bda4a2d816..6671959e5d 100644 > --- a/hw/display/ati.c > +++ b/hw/display/ati.c > @@ -384,7 +384,10 @@ static uint64_t ati_mm_read(void *opaque, hwaddr addr, unsigned int size) > val = s->regs.crtc_pitch; > break; > case 0xf00 ... 0xfff: > - val = pci_default_read_config(&s->dev, addr - 0xf00, size); > + addr = addr - 0xf00; > + if (addr + size <= 0xff) { > + val = pci_default_read_config(&s->dev, addr, size); > + } > break; > case CUR_OFFSET: > val = s->regs.cur_offset; > -- > 2.26.2 > Regards, Daniel
Hello Phil, +-- On Thu, 4 Jun 2020, Philippe Mathieu-Daudé wrote --+ | >> @@ -1381,6 +1381,8 @@ uint32_t pci_default_read_config(PCIDevice *d, | >> + assert(address + len <= pci_config_size(d)); | | Yes, maybe I was not clear while reviewing v1, we need to audit the | callers and fix them first, then we can safely add the assert here. That's an elaborate task. Could we please make that into another patch series? +-- On Thu, 4 Jun 2020, Daniel P. Berrangé wrote --+ | On Thu, Jun 04, 2020 at 01:52:50AM +0530, P J P wrote: | > While reading PCI configuration bytes, a guest may send an | > address towards the end of the configuration space. It may lead | > to an OOB access issue. Add check to ensure 'address + size' is | > within PCI configuration space. | | Please include a CVE number for this security flaw if there is | one. Yes. For now I'll send a revised patch to fix this ati-vga OOB access issue. Thank you. -- Prasad J Pandit / Red Hat Product Security Team 8685 545E B54C 486B C6EB 271E E285 8B5A F050 DE8D
On Thu, Jun 04, 2020 at 02:48:59PM +0530, P J P wrote: > Hello Phil, > > +-- On Thu, 4 Jun 2020, Philippe Mathieu-Daudé wrote --+ > | >> @@ -1381,6 +1381,8 @@ uint32_t pci_default_read_config(PCIDevice *d, > | >> +   assert(address + len <= pci_config_size(d)); > | > | Yes, maybe I was not clear while reviewing v1, we need to audit the > | callers and fix them first, then we can safely add the assert here. > > That's an elaborate task. Could we please make that into another patch series? So let's make this a separate patch as defence in depth in case there are more bugs somewhere. Patch 1 is a CVE fix. Patch 2 is not. > +-- On Thu, 4 Jun 2020, Daniel P. Berrangé wrote --+ > | On Thu, Jun 04, 2020 at 01:52:50AM +0530, P J P wrote: > | > While reading PCI configuration bytes, a guest may send an > | > address towards the end of the configuration space. It may lead > | > to an OOB access issue. Add check to ensure 'address + size' is > | > within PCI configuration space. > | > | Please include a CVE number for this security flaw if there is > | one. > > Yes. For now I'll send a revised patch to fix this ati-vga OOB access issue. > > Thank you. > -- > Prasad J Pandit / Red Hat Product Security Team > 8685 545E B54C 486B C6EB 271E E285 8B5A F050 DE8D
diff --git a/hw/display/ati.c b/hw/display/ati.c index bda4a2d816..6671959e5d 100644 --- a/hw/display/ati.c +++ b/hw/display/ati.c @@ -384,7 +384,10 @@ static uint64_t ati_mm_read(void *opaque, hwaddr addr, unsigned int size) val = s->regs.crtc_pitch; break; case 0xf00 ... 0xfff: - val = pci_default_read_config(&s->dev, addr - 0xf00, size); + addr = addr - 0xf00; + if (addr + size <= 0xff) { + val = pci_default_read_config(&s->dev, addr, size); + } break; case CUR_OFFSET: val = s->regs.cur_offset;