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CVE-2021-47412

7.8 · HIGH

In the Linux kernel, the following vulnerability has been resolved: block: don't call rq_qos_ops->done_bio if the bio isn't tracked rq_qos framework is only applied on request based driver, so:…

Published May 21, 2024EPSS 0.23%

Overview

CVE-2021-47412 is a high-severity vulnerability. It was published on May 21, 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:

block: don't call rq_qos_ops->done_bio if the bio isn't tracked

rq_qos framework is only applied on request based driver, so:

1) rq_qos_done_bio() needn't to be called for bio based driver

2) rq_qos_done_bio() needn't to be called for bio which isn't tracked,

such as bios ended from error handling code.

Especially in bio_endio():

1) request queue is referred via bio->bi_bdev->bd_disk->queue, which

may be gone since request queue refcount may not be held in above two

cases

2) q->rq_qos may be freed in blk_cleanup_queue() when calling into

__rq_qos_done_bio()

Fix the potential kernel panic by not calling rq_qos_ops->done_bio if

the bio isn't tracked. This way is safe because both ioc_rqos_done_bio()

and blkcg_iolatency_done_bio() are nop if the bio isn't tracked.

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/004b8f8a691205a93d9e80d98b786b2b97424d6eRefgit.kernel.org/stable/c/a647a524a46736786c95cdb553a070322ca096e3Refgit.kernel.org/stable/c/db60edbfff332a6a5477c367af8125f034570989Refgit.kernel.org/stable/c/004b8f8a691205a93d9e80d98b786b2b97424d6eRefgit.kernel.org/stable/c/a647a524a46736786c95cdb553a070322ca096e3Reflists.debian.org/debian-lts-announce/2025/10/msg00007.html

How CyberStrike helps

Frequently asked questions

What is CVE-2021-47412?

CVE-2021-47412 is a high-severity vulnerability. It was published on May 21, 2024 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2021-47412?

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-2021-47412?

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-2021-47412?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-47412 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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