SB20260727207 - Improper handling of exceptional conditions in Linux kernel s390 mm

Description

This security bulletin contains information about 1 vulnerability.

1) Improper handling of exceptional conditions (CVE-ID: CVE-2026-64369)

CWE-ID: CWE-755 - Improper Handling of Exceptional Conditions

CVSSv4: 6.8 [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]

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

The vulnerability exists due to improper exception handling in load_unaligned_zeropad() and the s390 secure storage access exception handler when reading unaligned data across page boundaries involving donated secure-execution pages. A local user can trigger the vulnerable kernel access pattern to cause a denial of service.

The issue can result in an endless exception loop when the second page access raises an exception for pages donated to the Ultravisor for secure execution purposes.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/37540b8c287fc817bdbd0c62bb75ad6eab0e5d03
• https://git.kernel.org/stable/c/be79d285bea70d0edd5015bd487311bfa8cbebc9
• https://git.kernel.org/stable/c/c94806905e02cc8e17a69c822d93c41743b7ffc5
• https://git.kernel.org/stable/c/c9e0f1517631ac08987f8385817119bccf2f1f12