CVE-2025-38257: s390/pkey: Prevent overflow in size calculation for memdup_user()

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-07-09 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: s390/pkey: Prevent overflow in size calculation for memdup_user() Number of apqn target list entries contained in 'nr_apqns' variable is determined by userspace via an ioctl call so the result of the product in calculation of size passed to memdup_user() may overflow. In this case the actual size of the allocated area and the value describing it won't be in sync leading to various types of unpredictable behaviour later. Use a proper memdup_array_user() helper which returns an error if an overflow is detected. Note that it is different from when nr_apqns is initially zero - that case is considered valid and should be handled in subsequent pkey_handler implementations. Found by Linux Verification Center (linuxtesting.org).

Affected products

Debian Linux: 11.0
Linux kernel: from 5.4 before 5.15.187; from 5.16 before 6.1.143; from 6.2 before 6.6.96; from 6.7 before 6.12.36; from 6.13 before 6.15.5; 6.16-rc1, 6.16-rc2, 6.16-rc3 — fixed in 5.15.187, 6.1.143, 6.12.36, 6.15.5, 6.6.96

How to fix

Upgrade to a fixed version: Linux kernel 5.15.187, 6.1.143, 6.12.36, 6.15.5. Check the vendor advisory for mitigations.

References

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