CVE-2020-27835: Use After Free
First published: Wed Nov 25 2020(Updated: )
A flaw use after free in the Linux kernel infiniband hfi1 driver was found in the way user calls Ioctl after open dev file and fork. A local user could use this flaw to crash the system.
Credit: secalert@redhat.com
| 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 |
| redhat/Linux kernel | <5.10 | 5.10 |
| Linux Infiniband HFI1 Driver | <=5.9 | |
| Linux Infiniband HFI1 Driver | =5.10-rc1 | |
| Linux Infiniband HFI1 Driver | =5.10-rc2 | |
| Linux Infiniband HFI1 Driver | =5.10-rc3 | |
| Linux Infiniband HFI1 Driver | =5.10-rc4 | |
| Linux Infiniband HFI1 Driver | =5.10-rc5 | |
| debian/linux | 5.10.223-1 5.10.234-1 6.1.123-1 6.1.128-1 6.12.12-1 6.12.17-1 |
Remedy
To mitigate this issue, prevent the module hfi1 from being loaded. Please see https://access.redhat.com/solutions/41278 for information on how to denylist a kernel module to prevent it from loading automatically.
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Reference Links
- https://www.cve.org/CVERecord?id=CVE-2020-27835 https://nvd.nist.gov/vuln/detail/CVE-2020-27835
- https://bugzilla.redhat.com/show_bug.cgi?id=1901709
- https://access.redhat.com/errata/RHSA-2021:1739
- https://access.redhat.com/errata/RHSA-2021:1578
- https://access.redhat.com/security/cve/cve-2020-27835
- https://launchpad.net/bugs/cve/CVE-2020-27835
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/infiniband/hw/hfi1/mmu_rb.c?id=3d2a9d642512c21a12d19b9250e7a835dcb41a79
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1906122
- https://access.redhat.com/solutions/41278
- https://git.kernel.org/linus/3d2a9d642512c21a12d19b9250e7a835dcb41a79
- https://security-tracker.debian.org/tracker/CVE-2020-27835
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-27835
- https://nvd.nist.gov/vuln/detail/CVE-2020-27835
- https://ubuntu.com/security/CVE-2020-27835
Frequently Asked Questions
What is the severity of CVE-2020-27835?
CVE-2020-27835 has a medium severity rating due to its potential to crash the system.
How do I fix CVE-2020-27835?
To fix CVE-2020-27835, upgrade to kernel versions 5.10-rc6 or later, or apply the relevant patches provided by your distribution.
Which versions are affected by CVE-2020-27835?
CVE-2020-27835 affects Linux kernel versions prior to 5.10-rc6, including earlier versions like 5.10-rc1 through 5.9.
Who is affected by CVE-2020-27835?
Local users on systems running the vulnerable versions of the Linux kernel with Infiniband hfi1 driver are primarily affected by CVE-2020-27835.
Can external users exploit CVE-2020-27835?
CVE-2020-27835 is a local privilege escalation vulnerability and cannot be exploited remotely by external users.
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