CVE-2021-47461: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: userfaultfd: fix a race between writeprotect and exit_mmap() A race is possible when a process exits, its VMAs are removed by exit_mmap() and at the same time userfaultfd_writeprotect() is called. The race was detected by KASAN on a development kernel, but it appears to be possible on vanilla kernels as well. Use mmget_not_zero() to prevent the race as done in other userfaultfd operations.

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CVSS v3.1 Score

4.7

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-362 CWE-362

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.7 — 5.10.76
linux	linux_kernel	5.11 — 5.14.15
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525 https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525 https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca

Frequently Asked Questions

What is CVE-2021-47461? +

In the Linux kernel, the following vulnerability has been resolved: userfaultfd: fix a race between writeprotect and exit_mmap() A race is possible when a process exits, its VMAs are removed by exit_mmap() and at the same time userfaultfd_writeprotect() is called. The race was detected by KASAN on a development kernel, but it appears to be possible on vanilla kernels as well. Use mmget_not_zero() to prevent the race as done in other userfaultfd operations. It has a CVSS v3.1 base score of 4.7 (MEDIUM).

How severe is CVE-2021-47461? +

CVE-2021-47461 has a CVSS v3.1 score of 4.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2021-47461? +

CVE-2021-47461 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2021-47461? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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