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redhatcveRedhat.comRH:CVE-2020-28974
HistoryDec 01, 2020 - 12:31 p.m.

CVE-2020-28974

2020-12-0112:31:07
redhat.com
access.redhat.com
41

0.0004 Low

EPSS

Percentile

5.2%

An out-of-bounds (OOB) SLAB memory access flaw was found in the Linux kernel’s fbcon driver module. A bounds check failure allows a local attacker with special user privileges to gain access to out-of-bounds memory, leading to a system crash or leaking of internal kernel information. The highest threat from this vulnerability is to system availability.

Mitigation

Add 'nomodeset' option as kernel boot parameter to disable frame buffering in /etc/default/grub, and run 'grub2-mkconfig -o /boot/grub2/grub.cfg' and reboot.

# cat /proc/cmdline   
BOOT_IMAGE=(hd0,msdos1)/vmlinuz-4.18.0-147.el8.x86_64 root=/dev/mapper/rhel_rhel8u2--1-root ro crashkernel=auto resume=/dev/mapper/rhel_rhel8u2--1-swap rd.lvm.lv=rhel_rhel8u2-1/root rd.lvm.lv=rhel_rhel8u2-1/swap nomodeset  
  
# ls -l /dev/fb*  
ls: cannot access '/dev/fb*': No such file or directory  

The above said mitigation does not so effect for rhel6 kernel , and is only applicable for rhel7/8.