Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2024-07-12T00:00:00 kernel: io_uring/io-wq: Use set_bit() and test_bit() at worker->flags 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H CWE-820

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:?) <snip> 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) <snip> 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.

A vulnerability was found in the Linux kernel's io_uring subsystem within the io_wq handling functions, where the issue stems from concurrent access to worker->flags, which can lead to data races when multiple tasks manipulate this structure simultaneously, which result in crashes, impacting the reliability of asynchronous I/O operations.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. Red Hat Enterprise Linux 9 2024-11-12T00:00:00Z RHSA-2024:9315 kernel-0:5.14.0-503.11.1.el9_5 Red Hat Enterprise Linux 9 2024-11-12T00:00:00Z RHSA-2024:9315 kernel-0:5.14.0-503.11.1.el9_5 Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Not affected kernel Red Hat Enterprise Linux 8 Not affected kernel-rt Red Hat Enterprise Linux 9 Affected kernel-rt https://www.cve.org/CVERecord?id=CVE-2024-39508 https://nvd.nist.gov/vuln/detail/CVE-2024-39508 https://lore.kernel.org/linux-cve-announce/2024071206-CVE-2024-39508-20c3@gregkh/T