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

blk-cgroup: fix leaks and online flag on radix_tree_insert failure

When radix_tree_insert() fails in blkg_create(), the error path has two
issues:

1. blkg->online is set to true unconditionally, even when the blkg was
never fully inserted. Move the assignment inside the success block.

2. The error path calls blkg_put() without first calling
percpu_ref_kill(). Because the refcount is still in percpu mode,
percpu_ref_put() only does this_cpu_sub() without checking for zero,
so blkg_release() is never triggered. This permanently leaks the
blkg memory, its percpu iostat, policy data, the parent blkg
reference, and the cgroup css reference — the latter preventing the
cgroup from ever being destroyed.

Fix by replacing blkg_put() with percpu_ref_kill(), matching the pattern
used in blkg_destroy().

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4817-1 linux-6.12 security update
Debian DLA Debian DLA DLA-4841-1 linux security update
Debian DSA Debian DSA DSA-6528-1 linux security update
Ubuntu USN Ubuntu USN USN-8961-1 Linux kernel vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Sat, 03 Oct 2026 11:15:00 +0000


Thu, 01 Oct 2026 17:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-401

Tue, 29 Sep 2026 13:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-772
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Low


Fri, 25 Sep 2026 07:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-401

Thu, 24 Sep 2026 16:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: fix leaks and online flag on radix_tree_insert failure When radix_tree_insert() fails in blkg_create(), the error path has two issues: 1. blkg->online is set to true unconditionally, even when the blkg was never fully inserted. Move the assignment inside the success block. 2. The error path calls blkg_put() without first calling percpu_ref_kill(). Because the refcount is still in percpu mode, percpu_ref_put() only does this_cpu_sub() without checking for zero, so blkg_release() is never triggered. This permanently leaks the blkg memory, its percpu iostat, policy data, the parent blkg reference, and the cgroup css reference — the latter preventing the cgroup from ever being destroyed. Fix by replacing blkg_put() with percpu_ref_kill(), matching the pattern used in blkg_destroy().
Title blk-cgroup: fix leaks and online flag on radix_tree_insert failure
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-03T10:57:30.314Z

Reserved: 2026-09-18T17:59:28.789Z

Link: CVE-2026-93795

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-24T17:17:12.270

Modified: 2026-10-03T11:17:49.107

Link: CVE-2026-93795

cve-icon Redhat

Severity : Low

Publid Date: 2026-09-24T00:00:00Z

Links: CVE-2026-93795 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-01T20:15:12Z

Weaknesses