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CVE-2021-47492

7.8 · HIGH

In the Linux kernel, the following vulnerability has been resolved: mm, thp: bail out early in collapse_file for writeback page Currently collapse_file does not explicitly check PG_writeback, ins…

Published May 22, 2024EPSS 0.22%

Overview

CVE-2021-47492 is a high-severity vulnerability. It was published on May 22, 2024 and has a CVSS 3.1 base score of 7.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

mm, thp: bail out early in collapse_file for writeback page

Currently collapse_file does not explicitly check PG_writeback, instead,

page_has_private and try_to_release_page are used to filter writeback

pages. This does not work for xfs with blocksize equal to or larger

than pagesize, because in such case xfs has no page->private.

This makes collapse_file bail out early for writeback page. Otherwise,

xfs end_page_writeback will panic as follows.

page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:ffff0003f88c86a8 index:0x0 pfn:0x84ef32

aops:xfs_address_space_operations [xfs] ino:30000b7 dentry name:"libtest.so"

flags: 0x57fffe0000008027(locked|referenced|uptodate|active|writeback)

raw: 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8

raw: 0000000000000000 0000000000000000 00000000ffffffff ffff0000c3e9a000

page dumped because: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) + 127

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/5e669d8ab30ab61dec3c36e27b4711f07611e6fcRefgit.kernel.org/stable/c/69a7fa5cb0de06c8956b040f19a7248c8c8308caRefgit.kernel.org/stable/c/74c42e1baacf206338b1dd6b6199ac964512b5bbRefgit.kernel.org/stable/c/5e669d8ab30ab61dec3c36e27b4711f07611e6fcRefgit.kernel.org/stable/c/69a7fa5cb0de06c8956b040f19a7248c8c8308caRefgit.kernel.org/stable/c/74c42e1baacf206338b1dd6b6199ac964512b5bb

How CyberStrike helps

Frequently asked questions

What is CVE-2021-47492?

CVE-2021-47492 is a high-severity vulnerability. It was published on May 22, 2024 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2021-47492?

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-47492?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-47492?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-47492 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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