CVE-2024-31076: 
Linux Kernel vulnerability analysis and mitigation

CVE-2024-31076 is a vulnerability in the Linux kernel related to interrupt handling during CPU offline operations. The issue was discovered in the genirq/cpuhotplug and x86/vector components, specifically involving a vector leak that occurs during CPU offline processes. The vulnerability was disclosed in June 2024 and affects the Linux kernel's interrupt handling mechanism (Kernel Git).

The vulnerability stems from the absence of IRQDMOVEPCNTXT flag, which affects interrupt affinity reconfiguration via procfs. When an interrupt affinity is changed, the reconfiguration is deferred until the next trigger on the original CPU. During this process, a vector is allocated from the new CPU, but the old vector on the original CPU isn't immediately reclaimed. Instead, it's marked with apicd->moveinprogress flag for later cleanup. A race condition occurs when the old CPU goes offline before the interrupt triggers on the new CPU, leading to an unreclaimed vector in vector_matrix (Kernel Git).

The vulnerability results in a CPU vector leak in the system. When vectors remain unreclaimed in the vector_matrix, it can lead to resource exhaustion over time, potentially affecting system stability and performance (Kernel Git).

The issue has been patched by modifying the vector cleanup process. The fix involves moving the irqforcecompletemove() invocation before the irqneedsfixup() call to ensure proper vector reclamation, and adding additional cleanup in _vectorschedulecleanup() with warning messages. The patch has been integrated into various Linux distributions, including Red Hat Enterprise Linux (RHSA-2024:9498).