From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Cathy Avery <cavery@redhat.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Bjorn Helgaas <helgaas@kernel.org>
Subject: [PATCH v2] x86: don't assume all fb devices are PCI devices
Date: Mon, 14 Mar 2016 15:42:57 +0100 [thread overview]
Message-ID: <1457966577-4006-1-git-send-email-vkuznets@redhat.com> (raw)
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 <vkuznets@redhat.com>
---
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
next reply other threads:[~2016-03-14 14:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-14 14:42 Vitaly Kuznetsov [this message]
2016-03-14 15:28 ` [PATCH v2] x86: don't assume all fb devices are PCI devices Bjorn Helgaas
2016-03-14 16:33 ` Ingo Molnar
2016-03-14 16:48 ` Vitaly Kuznetsov
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