High · published May 21, 2024
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.
| Product | Versions | Fixed in |
|---|---|---|
| linux/linux_kernel | < 4.4.286 | 4.4.286 |
| linux/linux_kernel | ≥ 4.5, < 4.9.285 | 4.9.285 |
| linux/linux_kernel | ≥ 4.10, < 4.14.249 | 4.14.249 |
| linux/linux_kernel | ≥ 4.15, < 4.19.209 | 4.19.209 |
| linux/linux_kernel | ≥ 4.20, < 5.4.151 | 5.4.151 |
| linux/linux_kernel | ≥ 5.5, < 5.10.71 | 5.10.71 |
| linux/linux_kernel | ≥ 5.11, < 5.14.10 | 5.14.10 |