CVE-2025-39788

/// Technical 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.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References