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 <[email protected]> --- 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; -- 2.5.0
