Race Condition Affecting kernel-rt-debug-kvm package, versions *
Threat Intelligence
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Test your applications- Snyk IDSNYK-CENTOS7-KERNELRTDEBUGKVM-8018100
- published17 Sept 2024
- disclosed13 Sept 2024
Introduced: 13 Sep 2024
CVE-2024-46704 (opens in a new tab)How to fix?
There is no fixed version for Centos:7 kernel-rt-debug-kvm.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-rt-debug-kvm package and not the kernel-rt-debug-kvm package as distributed by Centos.
See How to fix? for Centos:7 relevant fixed versions and status.
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.