CVE-2020-28974
First published: Mon Nov 09 2020(Updated: )
A slab-out-of-bounds read in fbcon in the Linux kernel before 5.9.7 could be used by local attackers to read privileged information or potentially crash the kernel, aka CID-3c4e0dff2095. This occurs because KD_FONT_OP_COPY in drivers/tty/vt/vt.c can be used for manipulations such as font height.
Credit: cve@mitre.org cve@mitre.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| redhat/kernel-rt | <0:4.18.0-305.rt7.72.el8 | 0:4.18.0-305.rt7.72.el8 |
| redhat/kernel | <0:4.18.0-305.el8 | 0:4.18.0-305.el8 |
| Linux Linux kernel | <5.9.7 | |
| Debian Debian Linux | =9.0 | |
| debian/linux | 5.10.223-1 5.10.226-1 6.1.115-1 6.1.119-1 6.12.6-1 |
Remedy
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.
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Reference Links
- https://www.cve.org/CVERecord?id=CVE-2020-28974 https://nvd.nist.gov/vuln/detail/CVE-2020-28974
- https://bugzilla.redhat.com/show_bug.cgi?id=1903126
- https://access.redhat.com/errata/RHSA-2021:1739
- https://access.redhat.com/errata/RHSA-2021:1578
- https://access.redhat.com/security/cve/cve-2020-28974
- http://www.openwall.com/lists/oss-security/2020/11/25/1
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.9.7
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3c4e0dff2095c579b142d5a0693257f1c58b4804
- https://lists.debian.org/debian-lts-announce/2020/12/msg00015.html
- https://lists.debian.org/debian-lts-announce/2020/12/msg00027.html
- https://seclists.org/oss-sec/2020/q4/104
- https://security.netapp.com/advisory/ntap-20210108-0003/
- https://launchpad.net/bugs/cve/CVE-2020-28974
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1903128
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1903934
- https://git.kernel.org/linus/3c4e0dff2095c579b142d5a0693257f1c58b4804
- https://www.openwall.com/lists/oss-security/2020/11/09/2
- https://security-tracker.debian.org/tracker/CVE-2020-28974
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-28974
- https://nvd.nist.gov/vuln/detail/CVE-2020-28974
- https://ubuntu.com/security/CVE-2020-28974
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