Linux Kernel up to 5.17.1 last_bfqq_created denial of service

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 5.17.1. This affects the function last_bfqq_created. Such manipulation leads to denial of service. This vulnerability is uniquely identified as CVE-2021-47646. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 5.17.1. It has been rated as critical. Affected by this issue is the function last_bfqq_created. The manipulation with an unknown input leads to a denial of service vulnerability. Using CWE to declare the problem leads to CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. Impacted is availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: Revert "Revert "block, bfq: honor already-setup queue merges"" A crash [1] happened to be triggered in conjunction with commit 2d52c58b9c9b ("block, bfq: honor already-setup queue merges"). The latter was then reverted by commit ebc69e897e17 ("Revert "block, bfq: honor already-setup queue merges""). Yet, the reverted commit was not the one introducing the bug. In fact, it actually triggered a UAF introduced by a different commit, and now fixed by commit d29bd41428cf ("block, bfq: reset last_bfqq_created on group change"). So, there is no point in keeping commit 2d52c58b9c9b ("block, bfq: honor already-setup queue merges") out. This commit restores it. [1] https://bugzilla.kernel.org/show_bug.cgi?id=214503

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2021-47646 since 02/26/2025. There are known technical details, but no exploit is available.

Upgrading to version 4.19.238, 5.4.189, 5.10.110, 5.15.33, 5.16.19 or 5.17.2 eliminates this vulnerability. Applying the patch f990f0985eda59d4f29fc83fcf300c92b1225d39/931aff627469a75c77b9fd3823146d0575afffd6/cc051f497eac9d8a0d816cd4bffa3415f2724871/65d8a737452e88f251fe5d925371de6d606df613/abc2129e646af7b43025d90a071f83043f1ae76c/4083925bd6dc89216d156474a8076feec904e607/15729ff8143f8135b03988a100a19e66d7cb7ecd is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 4.19.237
• 5.4.188
• 5.10.109
• 5.15.0
• 5.15.1
• 5.15.2
• 5.15.3
• 5.15.4
• 5.15.5
• 5.15.6
• 5.15.7
• 5.15.8
• 5.15.9
• 5.15.10
• 5.15.11
• 5.15.12
• 5.15.13
• 5.15.14
• 5.15.15
• 5.15.16
• 5.15.17
• 5.15.18
• 5.15.19
• 5.15.20
• 5.15.21
• 5.15.22
• 5.15.23
• 5.15.24
• 5.15.25
• 5.15.26
• 5.15.27
• 5.15.28
• 5.15.29
• 5.15.30
• 5.15.31
• 5.15.32
• 5.16.0
• 5.16.1
• 5.16.2
• 5.16.3
• 5.16.4
• 5.16.5
• 5.16.6
• 5.16.7
• 5.16.8
• 5.16.9
• 5.16.10
• 5.16.11
• 5.16.12
• 5.16.13
• 5.16.14
• 5.16.15
• 5.16.16
• 5.16.17
• 5.16.18
• 5.17.0
• 5.17.1

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

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