CVE-2024-57891: 
Linux Debian vulnerability analysis and mitigation

CVE-2024-57891 is a vulnerability discovered in the Linux kernel's schedext component, specifically in the scxopsbypass() function. The issue was identified when an outer irqsave/restore locking mechanism failed to properly convert an inner rqunlockirqrestore() to rqunlock(), which could lead to premature IRQ re-enabling. The vulnerability was disclosed on January 15, 2025, affecting specific versions of the Linux kernel (Red Hat CVE, NVD).

The vulnerability stems from a coding error in the kernel's scheduler extension (schedext) component. The issue occurs in the scxops_bypass() function where an incorrect IRQ restore operation could prematurely re-enable interrupts. The vulnerability has been assigned a CVSS v3.1 base score of 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H), indicating moderate severity with local access required (Red Hat CVE).

The vulnerability can trigger system warnings and potentially lead to interrupt handling issues. When exploited, it causes the system to generate warnings about invalid IRQ restore operations, which could affect system stability and proper interrupt handling (Kernel Git).

A fix has been implemented by converting the rqunlockirqrestore() call to rq_unlock() in the affected code. The patch has been committed to the kernel repository and is identified by commit 18b2093f4598d8ee67a8153badc93f0fa7686b8a. Red Hat has confirmed that several versions of Red Hat Enterprise Linux (6, 7, 8, and 9) and their RT variants are not affected by this vulnerability (Kernel Git, Red Hat CVE).