On Mon, Jan 24, 2022 at 10:52:22AM +0100, Helge Deller wrote:
On 1/23/22 23:30, Wei Liu wrote:
On Sun, Jan 23, 2022 at 10:27:56PM +0000, Michael Kelley (LINUX) wrote:
From: Wei Liu wei.liu@kernel.org Sent: Sunday, January 23, 2022 1:56 PM
On Sun, Jan 16, 2022 at 09:53:06PM +0000, Haiyang Zhang wrote:
-----Original Message----- From: Michael Kelley (LINUX) mikelley@microsoft.com Sent: Sunday, January 16, 2022 2:19 PM To: KY Srinivasan kys@microsoft.com; Haiyang Zhang
haiyangz@microsoft.com; Stephen
Hemminger sthemmin@microsoft.com; wei.liu@kernel.org; Wei Hu
weh@microsoft.com; Dexuan
Cui decui@microsoft.com; drawat.floss@gmail.com; hhei hhei@redhat.com;
linux-
kernel@vger.kernel.org; linux-hyperv@vger.kernel.org; linux-
fbdev@vger.kernel.org; dri-
devel@lists.freedesktop.org Cc: Michael Kelley (LINUX) mikelley@microsoft.com Subject: [PATCH 1/1] video: hyperv_fb: Fix validation of screen resolution
In the WIN10 version of the Synthetic Video protocol with Hyper-V, Hyper-V reports a list of supported resolutions as part of the protocol negotiation. The driver calculates the maximum width and height from the list of resolutions, and uses those maximums to validate any screen resolution specified in the video= option on the kernel boot line.
This method of validation is incorrect. For example, the list of supported resolutions could contain 1600x1200 and 1920x1080, both of which fit in an 8 Mbyte frame buffer. But calculating the max width and height yields 1920 and 1200, and 1920x1200 resolution does not fit in an 8 Mbyte frame buffer. Unfortunately, this resolution is accepted, causing a kernel fault when the driver accesses memory outside the frame buffer.
Instead, validate the specified screen resolution by calculating its size, and comparing against the frame buffer size. Delete the code for calculating the max width and height from the list of resolutions, since these max values have no use. Also add the frame buffer size to the info message to aid in understanding why a resolution might be rejected.
Fixes: 67e7cdb4829d ("video: hyperv: hyperv_fb: Obtain screen resolution from Hyper-V host") Signed-off-by: Michael Kelley mikelley@microsoft.com
[...]
Reviewed-by: Haiyang Zhang haiyangz@microsoft.com
Applied to hyperv-fixes. Thanks.
This fix got pulled into the fbdev/for-next tree by a new maintainer, Helge Deller. See https://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev.git/commi...
OK. I will drop it from hyperv-fixes. Thanks for letting me know!
Linus hasn't pulled my tree yet, and he will probably not before the next merge window. So, if this is an urgent bugfix for you, I can offer to drop it from the fbdev tree and that you take it through the hyperv-fixes tree. In that case you may add an Acked-by: Helge Deller deller@gmx.de. Just let me know what you prefer.
Hi Helge
Yes, I would like to upstream it as soon as possible so that it can propagate to stable trees and be backported by downstream vendors.
I will pick it up in hyperv-fixes. Please drop it from your for-next tree.
Thanks, Wei.
Helge