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Unrated severityNVD Advisory· Published Jul 12, 2024· Updated May 4, 2025

io_uring/io-wq: Use set_bit() and test_bit() at worker->flags

CVE-2024-39508

Description

In the Linux kernel, the following vulnerability has been resolved:

io_uring/io-wq: Use set_bit() and test_bit() at worker->flags

Utilize set_bit() and test_bit() on worker->flags within io_uring/io-wq to address potential data races.

The structure io_worker->flags may be accessed through various data paths, leading to concurrency issues. When KCSAN is enabled, it reveals data races occurring in io_worker_handle_work and io_wq_activate_free_worker functions.

BUG: KCSAN: data-race in io_worker_handle_work / io_wq_activate_free_worker write to 0xffff8885c4246404 of 4 bytes by task 49071 on cpu 28: io_worker_handle_work (io_uring/io-wq.c:434 io_uring/io-wq.c:569) io_wq_worker (io_uring/io-wq.c:?)

read to 0xffff8885c4246404 of 4 bytes by task 49024 on cpu 5: io_wq_activate_free_worker (io_uring/io-wq.c:? io_uring/io-wq.c:285) io_wq_enqueue (io_uring/io-wq.c:947) io_queue_iowq (io_uring/io_uring.c:524) io_req_task_submit (io_uring/io_uring.c:1511) io_handle_tw_list (io_uring/io_uring.c:1198)

Line numbers against commit 18daea77cca6 ("Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm").

These races involve writes and reads to the same memory location by different tasks running on different CPUs. To mitigate this, refactor the code to use atomic operations such as set_bit(), test_bit(), and clear_bit() instead of basic "and" and "or" operations. This ensures thread-safe manipulation of worker flags.

Also, move create_index to avoid holes in the structure.

Affected products

98

Patches

3
8a565304927f
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitvia osv
commit
1cbb0affb154
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitvia osv
commit
ab702c3483db
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.gitvia osv
commit

Vulnerability mechanics

Generated on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.

References

3

News mentions

0

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