SB20260529185 - Improper update of reference count in Linux kernel md persistent-data driver

Description

This security bulletin contains information about 1 vulnerability.

1) Improper update of reference count (CVE-ID: CVE-2026-46107)

CWE-ID: CWE-911 - Improper Update of Reference Count

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to improper reference count handling in the dm-thin rebalance_children function when rebalancing internal btree nodes with a shared child node. A local user can trigger the vulnerable code path to cause a denial of service.

The issue occurs because grandchild node reference counts are not increased when the shared child node is retained, which can lead to "device mapper: space map common: unable to decrement block" errors.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/09a65adc7d8bbfce06392cb6d375468e2728ead5
• https://git.kernel.org/stable/c/12161e03d33afce781f68fa11cc6060538862fad
• https://git.kernel.org/stable/c/323d252a4a378834e4fe68298ca61cfc5dd3a460
• https://git.kernel.org/stable/c/5ec0debbcfd43596e32c1239e993de06a704e04c
• https://git.kernel.org/stable/c/85311a585a26640760cd0f3349ab9f2905691044