CVE-2024-42124: 
Linux Kernel vulnerability analysis and mitigation

CVE-2024-42124 affects the Linux kernel's SCSI subsystem, specifically the qedf driver. The vulnerability was discovered when calling smpprocessorid() from preemptible code in qedfexecutetmf(), which results in a BUG_ON() condition when running on an RT (Real-Time) kernel. The issue was disclosed in July 2024 (Kernel Git).

The vulnerability occurs in the qedfexecutetmf() function within the SCSI qedf driver. The issue arises from calling smpprocessorid() in a preemptible code section, which is not allowed in RT kernel configurations. When triggered, it results in a kernel bug report with the message 'BUG: using smpprocessorid() in preemptible [00000000] code: sg_reset/3646' (Kernel Git).

When exploited, this vulnerability can cause a kernel panic on systems running RT (Real-Time) kernels, leading to a denial of service condition. This is particularly concerning for systems requiring real-time operations where system stability is crucial (Ubuntu Security).

The issue has been fixed by moving the smpprocessorid() call inside a non-preemptible section of code. Patches have been released for various Linux distributions including Ubuntu 20.04 LTS, 22.04 LTS, and 24.04 LTS. Users are advised to update their systems to the patched kernel versions (Ubuntu Security).