Ingo Molnar <[email protected]> writes: > * Bjorn Helgaas <[email protected]> wrote: > >> On Mon, Mar 14, 2016 at 03:42:57PM +0100, Vitaly Kuznetsov wrote: >> > When booting Hyper-V Generation 2 guests KASAN reports the following >> > out-of-bounds access: >> > >> > BUG: KASAN: slab-out-of-bounds in fb_is_primary_device+0x58/0x70 at addr >> > ffff880079cf0eb0 >> > Read of size 8 by task swapper/0/1 >> > ... >> > [<ffffffff81581308>] dump_stack+0x63/0x8b >> > [<ffffffff812e1f99>] print_trailer+0xf9/0x150 >> > [<ffffffff812e7344>] object_err+0x34/0x40 >> > [<ffffffff812e9630>] kasan_report_error+0x230/0x550 >> > [<ffffffff812e9ee8>] kasan_report+0x58/0x60 >> > [<ffffffff812e4500>] ? ___slab_alloc+0x80/0x490 >> > [<ffffffff81878a28>] ? fb_is_primary_device+0x58/0x70 >> > [<ffffffff812e87cd>] __asan_load8+0x5d/0x70 >> > [<ffffffff81878a28>] fb_is_primary_device+0x58/0x70 >> > [<ffffffff8162357a>] register_framebuffer+0xda/0x5b0 >> > [<ffffffff816234a0>] ? remove_conflicting_framebuffers+0x50/0x50 >> > ... >> > >> > The issue is caused by the to_pci_dev() call with no check that the given >> > info->device is in fact a pci device and some fb devices (Hyper-V FB, EFI >> > FB,...) are not. >> > >> > Signed-off-by: Vitaly Kuznetsov <[email protected]> >> >> Acked-by: Bjorn Helgaas <[email protected]> >> >> > --- >> > Changes since v1: use dev_is_pci() instead of full scan [Bjorn Helgaas]. >> > --- >> > arch/x86/video/fbdev.c | 7 +++---- >> > 1 file changed, 3 insertions(+), 4 deletions(-) >> > >> > diff --git a/arch/x86/video/fbdev.c b/arch/x86/video/fbdev.c >> > index d5644bb..9f2fe63 100644 >> > --- a/arch/x86/video/fbdev.c >> > +++ b/arch/x86/video/fbdev.c >> > @@ -18,12 +18,11 @@ int fb_is_primary_device(struct fb_info *info) >> > struct pci_dev *default_device = vga_default_device(); >> > struct resource *res = NULL; >> >> The initializations of "pci_dev" and "res" to NULL are now >> unnecessary. >> >> > >> > - if (device) >> > - pci_dev = to_pci_dev(device); >> > - >> > - if (!pci_dev) >> > + if (!device || !dev_is_pci(device)) >> > return 0; >> > >> > + pci_dev = to_pci_dev(device); >> > + >> > if (default_device) { >> > if (pci_dev == default_device) >> > return 1; >> >> The test for non-NULL "res" below is superfluous because we know >> "pci_dev" is non-NULL: >> >> res = &pci_dev->resource[PCI_ROM_RESOURCE]; >> if (res && res->flags & IORESOURCE_ROM_SHADOW) >> >> I think your patch is functionally correct, so it's up to you and the >> x86 guys whether you want to do these additional cleanups. > > I'd like to see those cleanups as well, no point in delaying them, right? >
Sure, will do v3! > btw., I'd suggest writing this: > >> res = &pci_dev->resource[PCI_ROM_RESOURCE]; > > as: > >> res = pci_dev->resource + PCI_ROM_RESOURCE; > -- Vitaly
