CVE-2025-39788: scsi: ufs: exynos: Fix programming of HCI_UTRL_NEXUS_TYPE

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: 2025-09-11 · updated 2026-10-19
Weakness: CWE-787

Description

In the Linux kernel, the following vulnerability has been resolved: scsi: ufs: exynos: Fix programming of HCI_UTRL_NEXUS_TYPE On Google gs101, the number of UTP transfer request slots (nutrs) is 32, and in this case the driver ends up programming the UTRL_NEXUS_TYPE incorrectly as 0. This is because the left hand side of the shift is 1, which is of type int, i.e. 31 bits wide. Shifting by more than that width results in undefined behaviour. Fix this by switching to the BIT() macro, which applies correct type casting as required. This ensures the correct value is written to UTRL_NEXUS_TYPE (0xffffffff on gs101), and it also fixes a UBSAN shift warning: UBSAN: shift-out-of-bounds in drivers/ufs/host/ufs-exynos.c:1113:21 shift exponent 32 is too large for 32-bit type 'int' For consistency, apply the same change to the nutmrs / UTMRL_NEXUS_TYPE write.

Affected products

Debian Linux: 11.0
Linux kernel: from 5.9 before 5.10.241; from 5.11 before 5.15.190; from 5.16 before 6.1.149; from 6.2 before 6.6.103; from 6.7 before 6.12.44; from 6.13 before 6.16.4 — fixed in 5.10.241, 5.15.190, 6.1.149, 6.12.44, 6.16.4, 6.6.103

How to fix

Upgrade to a fixed version: Linux kernel 5.10.241, 5.15.190, 6.1.149, 6.12.44. Check the vendor advisory for mitigations.

References

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