CVE-2024-26695: 
Linux Kernel vulnerability analysis and mitigation

CVE-2024-26695 is a null pointer dereference vulnerability discovered in the Linux kernel's crypto CCP (Cryptographic Co-Processor) component, specifically in the __sev_platform_shutdown_locked function. The vulnerability was discovered on April 3, 2024, affecting various Linux kernel versions from 5.10.137 through 6.8-rc3 (NVD).

The vulnerability occurs when the SEV platform device can be shutdown with a null psp_master, for example when using DEBUG_TEST_DRIVER_REMOVE. The issue was detected using KASAN (Kernel Address Sanitizer) which reported a null pointer dereference in the range [0x00000000000000f0-0x00000000000000f7]. The CVSS v3.1 base score is 5.5 (Medium) with vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (NVD, Kernel Patch).

The vulnerability can lead to a system crash (denial of service) when triggered, as demonstrated by the general protection fault and kernel crash logs. The impact is limited to availability with no direct impact on confidentiality or integrity (NVD).

The vulnerability requires local access and low privileges to exploit. It can be triggered through the DEBUG_TEST_DRIVER_REMOVE functionality, making it primarily a concern for testing environments or scenarios where local users have access to kernel driver operations (Kernel Patch).

The vulnerability has been patched in the Linux kernel by modifying the __sev_platform_shutdown_locked function to properly check for null psp_master before attempting to access sev_data. The fix has been backported to multiple kernel versions and is available in the kernel updates for various distributions including Ubuntu and Debian (Ubuntu Notice, Debian Notice).