CVE-2021-47383

In the Linux kernel, the following vulnerability has been resolved: tty:
Fix out-of-bound vmalloc access in imageblit This issue happens when a
userspace program does an ioctl FBIOPUT_VSCREENINFO passing the
fb_var_screeninfo struct containing only the fields xres, yres, and
bits_per_pixel with values. If this struct is the same as the previous
ioctl, the vc_resize() detects it and doesn’t call the resize_screen(),
leaving the fb_var_screeninfo incomplete. And this leads to the
updatescrollmode() calculates a wrong value to fbcon_display->vrows, which
makes the real_y() return a wrong value of y, and that value, eventually,
causes the imageblit to access an out-of-bound address value. To solve this
issue I made the resize_screen() be called even if the screen does not need
any resizing, so it will “fix and fill” the fb_var_screeninfo
independently.