From 743146db071c4a828159211a295d12ff4f61752f Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Tue, 15 Mar 2016 09:20:33 +0100 Subject: [PATCH] x86/video: Don't assume all FB devices are PCI devices 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 ... [] dump_stack+0x63/0x8b [] print_trailer+0xf9/0x150 [] object_err+0x34/0x40 [] kasan_report_error+0x230/0x550 [] kasan_report+0x58/0x60 [] ? ___slab_alloc+0x80/0x490 [] ? fb_is_primary_device+0x58/0x70 [] __asan_load8+0x5d/0x70 [] fb_is_primary_device+0x58/0x70 [] register_framebuffer+0xda/0x5b0 [] ? 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. While on it, clean up the function. Signed-off-by: Vitaly Kuznetsov Acked-by: Bjorn Helgaas Cc: Bjorn Helgaas Cc: Cathy Avery Cc: K. Y. Srinivasan Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1458030033-10122-1-git-send-email-vkuznets@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/video/fbdev.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/arch/x86/video/fbdev.c b/arch/x86/video/fbdev.c index d5644bbe8cba..9fd24846d094 100644 --- a/arch/x86/video/fbdev.c +++ b/arch/x86/video/fbdev.c @@ -14,26 +14,24 @@ int fb_is_primary_device(struct fb_info *info) { struct device *device = info->device; - struct pci_dev *pci_dev = NULL; struct pci_dev *default_device = vga_default_device(); - struct resource *res = NULL; + struct pci_dev *pci_dev; + struct resource *res; - 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; - else - return 0; + return 0; } - res = &pci_dev->resource[PCI_ROM_RESOURCE]; + res = pci_dev->resource + PCI_ROM_RESOURCE; - if (res && res->flags & IORESOURCE_ROM_SHADOW) + if (res->flags & IORESOURCE_ROM_SHADOW) return 1; return 0;