- Description
- 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.
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- NVD status
- Analyzed
CVSS 3.1
- Type
- Primary
- Base score
- 4.7
- Impact score
- 3.6
- Exploitability score
- 1
- Vector string
- CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
- Severity
- MEDIUM
- Hype score
- Not currently trending
[
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "E55C1263-DF43-41EF-8DA8-2BA68DF4FFFD",
"versionEndExcluding": "6.10.7",
"versionStartIncluding": "6.10"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:6.11:rc1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "8B3CE743-2126-47A3-8B7C-822B502CF119"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:6.11:rc2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "4DEB27E7-30AA-45CC-8934-B89263EF3551"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:6.11:rc3:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "E0005AEF-856E-47EB-BFE4-90C46899394D"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:6.11:rc4:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "39889A68-6D34-47A6-82FC-CD0BF23D6754"
}
],
"operator": "OR"
}
]
}
]