On Wed, Feb 13, 2019 at 11:14:06AM +0100, Eric Auger wrote: > pci_map_rom/pci_get_rom_size() performs memory access in the ROM. > In case the Memory Space accesses were disabled, readw() is likely to > crash the host with a synchronous external abort (aarch64).
Ouch. Is there an CVE for this? Also I think this can cause x86 machines to blow up. See https://xenbits.xen.org/xsa/advisory-120.html > > In case memory accesses were disabled, re-enable them before the call > and disable them back again just after. > > Signed-off-by: Eric Auger <[email protected]> > --- > drivers/vfio/pci/vfio_pci.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c > index ff60bd1ea587..96b8bbd909d7 100644 > --- a/drivers/vfio/pci/vfio_pci.c > +++ b/drivers/vfio/pci/vfio_pci.c > @@ -706,8 +706,10 @@ static long vfio_pci_ioctl(void *device_data, > break; > case VFIO_PCI_ROM_REGION_INDEX: > { > + bool mem_access_disabled; > void __iomem *io; > size_t size; > + u16 cmd; > > info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index); > info.flags = 0; > @@ -723,6 +725,13 @@ static long vfio_pci_ioctl(void *device_data, > break; > } > > + pci_read_config_word(pdev, PCI_COMMAND, &cmd); > + mem_access_disabled = !(cmd & PCI_COMMAND_MEMORY); > + if (mem_access_disabled) { > + cmd |= PCI_COMMAND_MEMORY; > + pci_write_config_word(pdev, PCI_COMMAND, cmd); > + } > + > /* Is it really there? */ > io = pci_map_rom(pdev, &size); > if (!io || !size) { > @@ -731,6 +740,11 @@ static long vfio_pci_ioctl(void *device_data, > } > pci_unmap_rom(pdev, io); > > + if (mem_access_disabled) { > + cmd &= ~PCI_COMMAND_MEMORY; > + pci_write_config_word(pdev, PCI_COMMAND, cmd); > + } > + > info.flags = VFIO_REGION_INFO_FLAG_READ; > break; > } > -- > 2.20.1 >
