CVE-2024-46704: In the Linux kernel, the following vulnerability has been resolved: workqueue: Fix spruious data race in __flush_work() When flushing a work item for…

PriorityP417medium4.7CVSS 3.1

AVLACHPRLUINSUCNINAH

EPSS

0.18%

7.2th percentile

In the Linux kernel, the following vulnerability has been resolved: workqueue: Fix spruious data race in __flush_work() When flushing a work item for cancellation, __flush_work() knows that it exclusively owns the work item through its PENDING bit. 134874e2eee9 ("workqueue: Allow cancel_work_sync() and disable_work() from atomic contexts on BH work items") added a read of @work->data to determine whether to use busy wait for BH work items that are being canceled. While the read is safe when @from_cancel, @work->data was read before testing @from_cancel to simplify code structure: data = *work_data_bits(work); if (from_cancel && !WARN_ON_ONCE(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_BH)) { While the read data was never used if !@from_cancel, this could trigger KCSAN data race detection spuriously: BUG: KCSAN: data-race in __flush_work / __flush_work write to 0xffff8881223aa3e8 of 8 bytes by task 3998 on cpu 0: instrument_write include/linux/instrumented.h:41 [inline] ___set_bit include/asm-generic/bitops/instrumented-non-atomic.h:28 [inline] insert_wq_barrier kernel/workqueue.c:3790 [inline] start_flush_work kernel/workqueue.c:4142 [inline] __flush_work+0x30b/0x570 kernel/workqueue.c:4178 flush_work kernel/workqueue.c:4229 [inline] ... read to 0xffff8881223aa3e8 of 8 bytes by task 50 on cpu 1: __flush_work+0x42a/0x570 kernel/workqueue.c:4188 flush_work kernel/workqueue.c:4229 [inline] flush_delayed_work+0x66/0x70 kernel/workqueue.c:4251 ... value changed: 0x0000000000400000 -> 0xffff88810006c00d Reorganize the code so that @from_cancel is tested before @work->data is accessed. The only problem is triggering KCSAN detection spuriously. This shouldn't need READ_ONCE() or other access qualifiers. No functional changes.

Affected

8 ranges

Vendor	Product	Version range	Fixed in
debian	linux	< linux 6.10.7-1 (forky)	linux 6.10.7-1 (forky)
linux	linux	—	—
linux	linux	>= 134874e2eee9380c2700411d4844cbc29297bc01 < 91d09642127a32fde231face2ff489af70eef316	91d09642127a32fde231face2ff489af70eef316
linux	linux	>= 134874e2eee9380c2700411d4844cbc29297bc01 < 8bc35475ef1a23b0e224f3242eb11c76cab0ea88	8bc35475ef1a23b0e224f3242eb11c76cab0ea88
linux	linux_kernel	—	—
linux	linux_kernel	>= 0 < 6.10.7-1	6.10.7-1
linux	linux_kernel	>= 0 < 6.10.7-1	6.10.7-1
linux	linux_kernel	>= 6.10 < 6.10.7	6.10.7

CVSS provenance

nvdv3.14.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

osv4.7MEDIUM

vendor_debian4.7LOW

vendor_redhat4.7MEDIUM

Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.