ACK: [SRU B/F PATCH 0/1] CVE-2021-33656

[Tim Gardner]

On 8/2/22 22:20, Cengiz Can wrote:
> [Impact]
> When setting font with malicous data by ioctl cmd PIO_FONT, kernel will
> write memory out of bounds.
> 
> [Fix]
> Fix was cherry-picked from closest stable trees.
> 
> An additional patch[1] seems to be under discussion (very recently)
> for removing leftover macros at `uapi/linux/kd.h`. Since it doesn't
> directly contribute to the fix, that patch was ignored.
> 
> [Test case]
> Compile and boot tested on KVM only.
> 
> [Potential regression]
> As discussed in mailing list and explained in the patch body, those
> ioctls seem to be archaic and not used by any known clients.
> 
> However I managed to find a complaint[2] from one of the users. It was
> suggested to switch to the newer API instead.
> 
> So there's a slight regression potantial, especially from users who
> change fonts of framebuffer console.
> 
> [1] https://lore.kernel.org/lkml/YuUdWoa7UFHmkNu9@kroah.com/T/#m536ff2bb888b82312895864479bc06ae52aaa8cf
> [2] https://www.spinics.net/lists/kernel/msg3985438.html
> 
> Jiri Slaby (1):
>    vt: drop old FONT ioctls
> 
>   drivers/tty/vt/vt.c       |  39 +---------
>   drivers/tty/vt/vt_ioctl.c | 149 --------------------------------------
>   include/linux/kd.h        |   8 --
>   3 files changed, 3 insertions(+), 193 deletions(-)
>   delete mode 100644 include/linux/kd.h
> 
Acked-by: Tim Gardner <tim.gardner at canonical.com>

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Tim Gardner
Canonical, Inc