CVE-2021-47646

Revert "Revert "block, bfq: honor already-setup queue merges""

State: Published
Severity: 7.8 High
Published: Feb 26, 2025
Updated: Aug 11, 2026
Reserved: Feb 26, 2025

Description

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

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	Linux
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	CISA-ADP

Weaknesses

CWE-416 Use After Free

Affected Products

Product	Versions
LinuxLinux	430a67f9d6169a7b3e328bceb2ef9542e4153c7c to before 65d8a737452e88f251fe5d925371de6d606df613Affected 430a67f9d6169a7b3e328bceb2ef9542e4153c7c to before abc2129e646af7b43025d90a071f83043f1ae76cAffected 430a67f9d6169a7b3e328bceb2ef9542e4153c7c to before 4083925bd6dc89216d156474a8076feec904e607Affected 430a67f9d6169a7b3e328bceb2ef9542e4153c7c to before 15729ff8143f8135b03988a100a19e66d7cb7ecdAffected
LinuxLinux	5.13Affected before 5.13Not affected 5.15.33 through 5.15.Not affected 5.16.19 through 5.16.Not affected 5.17.2 through 5.17.*Not affected 5.18 and laterNot affected

References

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