CVE-2023-53531
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-10-01

Last updated on: 2025-10-02

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: null_blk: fix poll request timeout handling When doing io_uring benchmark on /dev/nullb0, it's easy to crash the kernel if poll requests timeout triggered, as reported by David. [1] BUG: kernel NULL pointer dereference, address: 0000000000000008 Workqueue: kblockd blk_mq_timeout_work RIP: 0010:null_timeout_rq+0x4e/0x91 Call Trace: ? null_timeout_rq+0x4e/0x91 blk_mq_handle_expired+0x31/0x4b bt_iter+0x68/0x84 ? bt_tags_iter+0x81/0x81 __sbitmap_for_each_set.constprop.0+0xb0/0xf2 ? __blk_mq_complete_request_remote+0xf/0xf bt_for_each+0x46/0x64 ? __blk_mq_complete_request_remote+0xf/0xf ? percpu_ref_get_many+0xc/0x2a blk_mq_queue_tag_busy_iter+0x14d/0x18e blk_mq_timeout_work+0x95/0x127 process_one_work+0x185/0x263 worker_thread+0x1b5/0x227 This is indeed a race problem between null_timeout_rq() and null_poll(). null_poll() null_timeout_rq() spin_lock(&nq->poll_lock) list_splice_init(&nq->poll_list, &list) spin_unlock(&nq->poll_lock) while (!list_empty(&list)) req = list_first_entry() list_del_init() ... blk_mq_add_to_batch() // req->rq_next = NULL spin_lock(&nq->poll_lock) // rq->queuelist->next == NULL list_del_init(&rq->queuelist) spin_unlock(&nq->poll_lock) Fix these problems by setting requests state to MQ_RQ_COMPLETE under nq->poll_lock protection, in which null_timeout_rq() can safely detect this race and early return. Note this patch just fix the kernel panic when request timeout happen. [1] https://lore.kernel.org/all/[email protected]/
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Meta Information
Published
2025-10-01
Last Modified
2025-10-02
Generated
2026-06-16
AI Q&A
2025-10-01
EPSS Evaluated
2026-06-15
NVD
CVE-2023-53531
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
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Exploitability
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CWE ID Description
CWE-UNKNOWN
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Executive Summary

This vulnerability is a race condition in the Linux kernel's null_blk driver related to poll request timeout handling. When performing an io_uring benchmark on /dev/nullb0, if poll requests timeout, it can cause a kernel crash due to a NULL pointer dereference. The issue arises from a race between two functions, null_timeout_rq() and null_poll(), which manipulate poll request lists without proper synchronization. The fix involves setting the request state to MQ_RQ_COMPLETE under a lock to safely detect and handle the race, preventing kernel panic.

Impact Analysis

This vulnerability can cause the Linux kernel to crash (kernel panic) when certain timeout conditions occur during io_uring operations on /dev/nullb0. Such crashes can lead to system instability, downtime, and potential data loss or service interruption on affected systems.

Mitigation Strategies

Apply the patch that fixes the kernel panic caused by the null_blk poll request timeout handling race condition. This patch sets the request state to MQ_RQ_COMPLETE under nq->poll_lock protection, preventing the race between null_timeout_rq() and null_poll().

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