Messages in this thread | | | Date | Sat, 12 Mar 2016 16:48:31 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] x86: don't assume all fb devices are PCI devices |
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So I'd love to have an ACK from Bjorn. (Full mail quoted below)
Thanks,
Ingo
* Vitaly Kuznetsov <vkuznets@redhat.com> 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. fb_is_primary_device() is not on any performance critical > path, replace to_pci_dev() with raw scan. > > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> > --- > arch/x86/video/fbdev.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/video/fbdev.c b/arch/x86/video/fbdev.c > index d5644bb..f309d6c 100644 > --- a/arch/x86/video/fbdev.c > +++ b/arch/x86/video/fbdev.c > @@ -14,12 +14,18 @@ > int fb_is_primary_device(struct fb_info *info) > { > struct device *device = info->device; > - struct pci_dev *pci_dev = NULL; > + struct pci_dev *dev = NULL, *pci_dev = NULL; > struct pci_dev *default_device = vga_default_device(); > struct resource *res = NULL; > > - if (device) > - pci_dev = to_pci_dev(device); > + /* > + * We're not sure info->device is a pci device, do full scan instead > + * of to_pci_dev(). > + */ > + for_each_pci_dev(dev) { > + if (&dev->dev == device) > + pci_dev = dev; > + } > > if (!pci_dev) > return 0;
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