CVE-2025-21831: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-21831 affects the Linux kernel and involves a vulnerability in the PCI power management functionality. The issue was discovered on March 6, 2025, and specifically affects the TUXEDO Sirius 16 Gen 1 laptop with a specific old BIOS version. The vulnerability stems from a policy that allows PCIe ports to enter D3 power state during system suspend (NVD).

The vulnerability is caused by commit 9d26d3a8f1b0 which sets a policy allowing all PCIe ports to use D3 power state. When the system is suspended, if a port is not power manageable by the platform and won't be used for wakeup via PME, the ports enter D3hot state. While this policy generally makes sense from an OSPM perspective, it causes problems specifically on the TUXEDO Sirius 16 Gen 1 with older BIOS versions. The vulnerability has been assigned a CVSS v3.1 score of 5.5 (Low) with vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (Red Hat CVE).

The primary impact of this vulnerability is system stability, specifically manifesting as a system hang when attempting to wake up from suspend state. This affects systems with the specific combination of TUXEDO Sirius 16 Gen 1 hardware and older BIOS versions (Kernel Git).

A fix has been implemented through a kernel patch that adds a quirk for the root port of the problematic controller to ensure these root ports are not put into D3hot at suspend. The fix is specifically targeted at the affected Device + BIOS combination and has been merged into the mainline kernel. The patch is based on earlier work by Mario Limonciello and includes additional conditions to apply only to the specific affected hardware (Kernel Git).