ACK: [SRU Bionic PATCH 0/3] CVE-2021-33655

[Tim Gardner]

On 8/5/22 09:54, Cengiz Can wrote:
> [Impact]
> When sending malicous data to kernel by ioctl cmd FBIOPUT_VSCREENINFO,
> kernel will write memory out of bounds.
> 
> [Fix]
> MITRE entry points to a merge commit that contain six patches. Three of
> those were considered relevant.
> 
> commit 6c11df58fd1a ("fbmem: Check virtual screen sizes in fb_set_var()")
> commit e64242caef18 ("fbcon: Prevent that screen size is smaller than font size")
> commit 65a01e601dbb ("fbcon: Disallow setting font bigger than screen size")
> 
> Only the first of those three were backported as far as 4.14 stable.
> Second and third patches have backport candidates that are under review.
> 
> https://lore.kernel.org/all/20220804122734.121201-1-chenjun102@huawei.com/
> 
> (I didn't pick CONFIG_FB is_console_locked patch. It seems irrelevant).
> 
> [Test case]
> Compile and boot tested on KVM only.
> 
> [Potential regression]
> Somehow high due to changes being very new and not accepted to stable
> tree yet. fbcon must be thoroughly tested.
> 
> Helge Deller (3):
>    fbcon: Disallow setting font bigger than screen size
>    fbcon: Prevent that screen size is smaller than font size
>    fbmem: Check virtual screen sizes in fb_set_var()
> 
>   drivers/video/fbdev/core/fbcon.c | 33 ++++++++++++++++++++++++++++++++
>   drivers/video/fbdev/core/fbmem.c | 20 ++++++++++++++++---
>   include/linux/fbcon.h            |  4 ++++
>   3 files changed, 54 insertions(+), 3 deletions(-)
> 
Acked-by: Tim Gardner <tim.gardner at canonical.com>

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Tim Gardner
Canonical, Inc