• Vitaly Kuznetsov's avatar
    x86/video: Don't assume all FB devices are PCI devices · 743146db
    Vitaly Kuznetsov authored
    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.
    
    While on it, clean up the function.
    Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
    Acked-by: default avatarBjorn Helgaas <bhelgaas@google.com>
    Cc: Bjorn Helgaas <helgaas@kernel.org>
    Cc: Cathy Avery <cavery@redhat.com>
    Cc: K. Y. Srinivasan <kys@microsoft.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/1458030033-10122-1-git-send-email-vkuznets@redhat.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    743146db
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