CVE-2021-47383

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 7e71fcedfda6f7de18f850a6b36e78d78b04476faffected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 70aed03b1d5a5df974f456cdc8eedb213c94bb8baffected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 067c694d06040db6f0c65281bb358452ca6d85b9affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 8a6a240f52e14356386030d8958ae8b1761d2325affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 883f7897a25e3ce14a7f274ca4c73f49ac84002aaffected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < d570c48dd37dbe8fc6875d4461d01a9554ae2560affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 699d926585daa6ec44be556cdc1ab89e5d54557baffected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 3b0c406124719b625b1aba431659f5cdc24a982caffected
LinuxLinux2.6.12affected
LinuxLinux0 < 2.6.12unaffected
LinuxLinux4.4.286 <= 4.4.*unaffected
LinuxLinux4.9.285 <= 4.9.*unaffected
LinuxLinux4.14.249 <= 4.14.*unaffected
LinuxLinux4.19.209 <= 4.19.*unaffected
LinuxLinux5.4.151 <= 5.4.*unaffected
LinuxLinux5.10.71 <= 5.10.*unaffected
LinuxLinux5.14.10 <= 5.14.*unaffected
LinuxLinux5.15 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

CVE Program Container

Additional References

References