FKIE_CVE-2026-72420
Vulnerability from fkie_nvd - Published: 2026-08-15 06:22 - Updated: 2026-08-17 06:19
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
md/raid5: avoid R5_Overlap races while breaking stripe batches
KCSAN report a race in break_stripe_batch_list() vs. raid5_make_request()
on sh->dev[i].flags (plain word write vs. atomic bit op)..
and .. one possible scenario is:
CPU1 CPU2
break_stripe_batch_list(sh1)
-> handle sh2
-> lock(sh2)
-> sh2->batch_head = NULL
-> unlock(sh2)
-> test_and_clear_bit(R5_Overlap, sh2->dev[i].flags)
-> wake_up_bit(sh2->dev[i].flags)
raid5_make_request()
-> add_all_stripe_bios(sh2)
-> lock(sh2)
-> stripe_bio_overlaps(sh2) returns true
batch_head is NULL, so new bio overlap
exist bio on sh2 -> true
-> set_bit(R5_Overlap, sh2->dev[i].flags)
-> unlock(sh2)
-> wait_on_bit(sh2->dev[i].flags)
-> sh2->dev[i].flags = sh1->dev[i].flags & ~R5_Overlap
No wait_up_bit(), CPU2 could be wait_on_bit() forever...
Fix by :
- Expand the protect zone.
- Use batch_head's device flag's snaphot when no held head_sh->stripe_lock.
- Move sh/head_sh->batch_head = NULL to the end of protected zone , and ,
any concurrent add_all_stripe_bios() grabs sh->stripe_lock now either:
- see batch_head != null, and , is rejected by stripe_bio_overlaps()
under the lock (no R5_Overlap wait ) , or ,
- sees batch_head == NULL, only after dev[i].flags has already been
set and the prior R5_Overlap waiters worken.
KCSAN report:
================================================
BUG: KCSAN: data-race in break_stripe_batch_list / raid5_make_request
write (marked) to 0xffff8e89c8117548 of 8 bytes by task 4042 on cpu 0:
raid5_make_request+0xea0/0x2930
md_handle_request+0x4a2/0xa40
md_submit_bio+0x109/0x1a0
__submit_bio+0x2ec/0x390
submit_bio_noacct_nocheck+0x457/0x710
submit_bio_noacct+0x2a7/0xc20
submit_bio+0x56/0x250
blkdev_direct_IO+0x54c/0xda0
blkdev_write_iter+0x38f/0x570
aio_write+0x22b/0x490
io_submit_one+0xa51/0xf70
__x64_sys_io_submit+0xf7/0x220
x64_sys_call+0x1907/0x1c60
do_syscall_64+0x130/0x570
entry_SYSCALL_64_after_hwframe+0x76/0x7e
read to 0xffff8e89c8117548 of 8 bytes by task 4010 on cpu 5:
break_stripe_batch_list+0x249/0x480
handle_stripe_clean_event+0x720/0x9b0
handle_stripe+0x32fb/0x4500
handle_active_stripes.isra.0+0x6e0/0xa50
raid5d+0x7e0/0xba0
md_thread+0x15a/0x2d0
kthread+0x1e3/0x220
ret_from_fork+0x37a/0x410
ret_from_fork_asm+0x1a/0x30
value changed: 0x0000000000000019 -> 0x0000000000000099 --> R5_Overlap
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/md/raid5.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "8031b0d02bd221a5f9add4357e291fc2a527b83a",
"status": "affected",
"version": "fb642b92c267beeefd352af9bc461eac93a7552c",
"versionType": "git"
},
{
"lessThan": "4d919c9b770996365806b6c8d701912d52baa306",
"status": "affected",
"version": "fb642b92c267beeefd352af9bc461eac93a7552c",
"versionType": "git"
},
{
"lessThan": "d684b72dfbd320623ccaab0779aa841190488e7c",
"status": "affected",
"version": "fb642b92c267beeefd352af9bc461eac93a7552c",
"versionType": "git"
},
{
"lessThan": "55b77337bdd088c77461588e5ec094421b89911b",
"status": "affected",
"version": "fb642b92c267beeefd352af9bc461eac93a7552c",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/md/raid5.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.1"
},
{
"lessThan": "4.1",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmd/raid5: avoid R5_Overlap races while breaking stripe batches\n\nKCSAN report a race in break_stripe_batch_list() vs. raid5_make_request()\non sh-\u003edev[i].flags (plain word write vs. atomic bit op)..\n\nand .. one possible scenario is:\n\nCPU1 CPU2\nbreak_stripe_batch_list(sh1)\n-\u003e handle sh2\n-\u003e lock(sh2)\n-\u003e sh2-\u003ebatch_head = NULL\n-\u003e unlock(sh2)\n-\u003e test_and_clear_bit(R5_Overlap, sh2-\u003edev[i].flags)\n-\u003e wake_up_bit(sh2-\u003edev[i].flags)\n raid5_make_request()\n -\u003e add_all_stripe_bios(sh2)\n -\u003e lock(sh2)\n -\u003e stripe_bio_overlaps(sh2) returns true\n\t\t\t\t batch_head is NULL, so new bio overlap\n\t\t\t\t exist bio on sh2 -\u003e true\n -\u003e set_bit(R5_Overlap, sh2-\u003edev[i].flags)\n -\u003e unlock(sh2)\n -\u003e wait_on_bit(sh2-\u003edev[i].flags)\n-\u003e sh2-\u003edev[i].flags = sh1-\u003edev[i].flags \u0026 ~R5_Overlap\n\nNo wait_up_bit(), CPU2 could be wait_on_bit() forever...\n\nFix by :\n- Expand the protect zone.\n- Use batch_head\u0027s device flag\u0027s snaphot when no held head_sh-\u003estripe_lock.\n- Move sh/head_sh-\u003ebatch_head = NULL to the end of protected zone , and ,\n any concurrent add_all_stripe_bios() grabs sh-\u003estripe_lock now either:\n\t- see batch_head != null, and , is rejected by stripe_bio_overlaps()\n\t under the lock (no R5_Overlap wait ) , or ,\n\t- sees batch_head == NULL, only after dev[i].flags has already been\n\t set and the prior R5_Overlap waiters worken.\n\nKCSAN report:\n================================================\n BUG: KCSAN: data-race in break_stripe_batch_list / raid5_make_request\n\n write (marked) to 0xffff8e89c8117548 of 8 bytes by task 4042 on cpu 0:\n raid5_make_request+0xea0/0x2930\n md_handle_request+0x4a2/0xa40\n md_submit_bio+0x109/0x1a0\n __submit_bio+0x2ec/0x390\n submit_bio_noacct_nocheck+0x457/0x710\n submit_bio_noacct+0x2a7/0xc20\n submit_bio+0x56/0x250\n blkdev_direct_IO+0x54c/0xda0\n blkdev_write_iter+0x38f/0x570\n aio_write+0x22b/0x490\n io_submit_one+0xa51/0xf70\n __x64_sys_io_submit+0xf7/0x220\n x64_sys_call+0x1907/0x1c60\n do_syscall_64+0x130/0x570\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\n read to 0xffff8e89c8117548 of 8 bytes by task 4010 on cpu 5:\n break_stripe_batch_list+0x249/0x480\n handle_stripe_clean_event+0x720/0x9b0\n handle_stripe+0x32fb/0x4500\n handle_active_stripes.isra.0+0x6e0/0xa50\n raid5d+0x7e0/0xba0\n md_thread+0x15a/0x2d0\n kthread+0x1e3/0x220\n ret_from_fork+0x37a/0x410\n ret_from_fork_asm+0x1a/0x30\n\n value changed: 0x0000000000000019 -\u003e 0x0000000000000099 --\u003e R5_Overlap"
}
],
"id": "CVE-2026-72420",
"lastModified": "2026-08-17T06:19:09.110",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 2.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-08-15T06:22:15.743",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/4d919c9b770996365806b6c8d701912d52baa306"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/55b77337bdd088c77461588e5ec094421b89911b"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/8031b0d02bd221a5f9add4357e291fc2a527b83a"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/d684b72dfbd320623ccaab0779aa841190488e7c"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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