CVE-2023-53531: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-53531 is a vulnerability discovered in the Linux kernel affecting the nullblk driver's poll request timeout handling functionality. When performing iouring benchmark operations on /dev/nullb0, the kernel can crash if poll requests timeout is triggered. The vulnerability was reported and included in the NVD dataset in October 2025 (NVD).

The vulnerability stems from a race condition between nulltimeoutrq() and nullpoll() functions. The issue occurs in the handling of poll requests and their timeout mechanisms, which can lead to a kernel NULL pointer dereference at address 0x0000000000000008. The vulnerability manifests in the Workqueue: kblockd blkmqtimeoutwork process (NVD).

When exploited, this vulnerability can cause a kernel crash through a NULL pointer dereference, potentially leading to denial of service conditions. The issue specifically affects systems utilizing the nullblk driver with iouring benchmarking operations (NVD).

The fix involves setting requests state to MQRQCOMPLETE under nq->polllock protection, which allows nulltimeout_rq() to safely detect the race condition and return early. This patch specifically addresses the kernel panic that occurs when request timeout happens (NVD).