linux-kernel - Re: [PATCH v3] x86: don't assume all fb devices are PCI devices

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Date:	Tue, 15 Mar 2016 11:09:46 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Cathy Avery <cavery@...hat.com>,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Bjorn Helgaas <helgaas@...nel.org>
Subject: Re: [PATCH v3] x86: don't assume all fb devices are PCI devices


* Vitaly Kuznetsov <vkuznets@...hat.com> wrote:

> 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, cleanup the function.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
> Changes since v2: cleanup fb_is_primary_device() [Bjorn Helgaas, Ingo Molnar].

Applied, thanks!

I also added Bjorn's Acked-by to the commit, as the only change from the last 
version are the cleanups.

Thanks,

	Ingo