Bug 1899177 (CVE-2020-28915) - CVE-2020-28915 kernel: out-of-bounds read in fbcon_get_font function
Summary: CVE-2020-28915 kernel: out-of-bounds read in fbcon_get_font function
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2020-28915
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1899178 1904373 1904374 1904375 1904376 1904377 2064762 2076348
Blocks: 1899179
TreeView+ depends on / blocked
 
Reported: 2020-11-18 16:43 UTC by Guilherme de Almeida Suckevicz
Modified: 2024-03-25 17:08 UTC (History)
46 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
An out-of-bounds (OOB) memory access flaw was found in fbcon_get_font() in drivers/video/fbdev/core/fbcon.c in fbcon driver module in the Linux kernel. A bound check failure allows a local attacker with special user privilege to gain access to out-of-bounds memory, leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to integrity and system availability.
Clone Of:
Environment:
Last Closed: 2022-12-03 17:03:21 UTC
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2022:5316 0 None None None 2022-06-28 18:31:59 UTC
Red Hat Product Errata RHSA-2022:5344 0 None None None 2022-06-28 12:25:55 UTC

Description Guilherme de Almeida Suckevicz 2020-11-18 16:43:35 UTC 
An out-of-bounds (OOB) memory access flaw was found in fbcon_get_font() in drivers/video/fbdev/core/fbcon.c in fbcon driver module in the Linux kernel. A bound check failure may allow a local attacker with special user privilege to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to system availability.

Reference:
https://syzkaller.appspot.com/bug?id=08b8be45afea11888776f897895aef9ad1c3ecfd
Comment 1 Guilherme de Almeida Suckevicz 2020-11-18 16:45:00 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1899178]
Comment 2 Justin M. Forbes 2020-11-18 17:39:09 UTC 
This was fixed for Fedora with the 5.8.15 stable kernel updates.
Comment 10 Rohit Keshri 2020-12-12 17:17:08 UTC 
Mitigation:

Add 'nomodeset' option as kernel boot parameter to disable frame buffering (edit /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
~~~
Comment 28 errata-xmlrpc 2022-06-28 12:25:50 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2022:5344 https://access.redhat.com/errata/RHSA-2022:5344
Comment 29 errata-xmlrpc 2022-06-28 18:31:53 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2022:5316 https://access.redhat.com/errata/RHSA-2022:5316
Comment 34 Product Security DevOps Team 2022-12-03 17:03:16 UTC 
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2020-28915
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