ghsa-mgxj-66hj-35x8
Vulnerability from github
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] setbit 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": [],
"aliases": [
"CVE-2024-46704"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-09-13T07:15:05Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nworkqueue: Fix spruious data race in __flush_work()\n\nWhen flushing a work item for cancellation, __flush_work() knows that it\nexclusively owns the work item through its PENDING bit. 134874e2eee9\n(\"workqueue: Allow cancel_work_sync() and disable_work() from atomic\ncontexts on BH work items\") added a read of @work-\u003edata to determine whether\nto use busy wait for BH work items that are being canceled. While the read\nis safe when @from_cancel, @work-\u003edata was read before testing @from_cancel\nto simplify code structure:\n\n\tdata = *work_data_bits(work);\n\tif (from_cancel \u0026\u0026\n\t !WARN_ON_ONCE(data \u0026 WORK_STRUCT_PWQ) \u0026\u0026 (data \u0026 WORK_OFFQ_BH)) {\n\nWhile the read data was never used if !@from_cancel, this could trigger\nKCSAN data race detection spuriously:\n\n ==================================================================\n BUG: KCSAN: data-race in __flush_work / __flush_work\n\n write to 0xffff8881223aa3e8 of 8 bytes by task 3998 on cpu 0:\n instrument_write include/linux/instrumented.h:41 [inline]\n ___set_bit include/asm-generic/bitops/instrumented-non-atomic.h:28 [inline]\n insert_wq_barrier kernel/workqueue.c:3790 [inline]\n start_flush_work kernel/workqueue.c:4142 [inline]\n __flush_work+0x30b/0x570 kernel/workqueue.c:4178\n flush_work kernel/workqueue.c:4229 [inline]\n ...\n\n read to 0xffff8881223aa3e8 of 8 bytes by task 50 on cpu 1:\n __flush_work+0x42a/0x570 kernel/workqueue.c:4188\n flush_work kernel/workqueue.c:4229 [inline]\n flush_delayed_work+0x66/0x70 kernel/workqueue.c:4251\n ...\n\n value changed: 0x0000000000400000 -\u003e 0xffff88810006c00d\n\nReorganize the code so that @from_cancel is tested before @work-\u003edata is\naccessed. The only problem is triggering KCSAN detection spuriously. This\nshouldn\u0027t need READ_ONCE() or other access qualifiers.\n\nNo functional changes.",
"id": "GHSA-mgxj-66hj-35x8",
"modified": "2024-09-19T15:30:49Z",
"published": "2024-09-13T09:30:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-46704"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8bc35475ef1a23b0e224f3242eb11c76cab0ea88"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/91d09642127a32fde231face2ff489af70eef316"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
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