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]> --- 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; - 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; -- 2.5.0
