CVE-2026-99256
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: dm cache: fix issue with background work locking dm cache used a rw_semaphore for background_work_lock. Write locks on rw_semaphores have strict owner semantics, but there was no guarantee that the process that locked background_work_lock was the same process that unlocked it. This can be easily seen using a kernel compiled with CONFIG_DEBUG_RWSEMS. Given a dm cache device <cache>, run: 'dmsetup suspend <cache> && dmsetup resume <cache>'. This will trigger a kernel warning: DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)) triggered by cache_resume(). To fix this, switch from a rw_semaphore to a spinlock and a wait queue. dm cache already has a wait queue and associated counter, migration_wait and nr_allocated_migrations, that was getting woken up when background work was getting completed, but wasn't actually used by anything. This is replaced by the background_work queue and counter.
Severity
Not scored
CVSS score
Not available
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-11-03 12:17:32.437000
Last modified
2026-11-03 12:17:32.437000
View original CVE JSON
{
"id": "CVE-2026-99256",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-11-03T12:17:32.437",
"lastModified": "2026-11-03T12:17:32.437",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm cache: fix issue with background work locking\n\ndm cache used a rw_semaphore for background_work_lock. Write locks on\nrw_semaphores have strict owner semantics, but there was no guarantee\nthat the process that locked background_work_lock was the same process\nthat unlocked it. This can be easily seen using a kernel compiled with\nCONFIG_DEBUG_RWSEMS. Given a dm cache device <cache>, run: 'dmsetup\nsuspend <cache> && dmsetup resume <cache>'. This will trigger a kernel\nwarning:\n\nDEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE))\n\ntriggered by cache_resume(). To fix this, switch from a rw_semaphore to\na spinlock and a wait queue. dm cache already has a wait queue and\nassociated counter, migration_wait and nr_allocated_migrations, that was\ngetting woken up when background work was getting completed, but wasn't\nactually used by anything. This is replaced by the background_work queue\nand counter."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"drivers/md/dm-cache-target.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
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"lessThan": "0c7a8cad7c96012a9157a189649e569d0390f384",
"versionType": "git",
"status": "affected"
},
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"programFiles": [
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
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"status": "affected"
},
{
"version": "0",
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"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.10.273",
"lessThanOrEqual": "5.10.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.15.224",
"lessThanOrEqual": "5.15.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.191",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.161",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.115",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.59",
"lessThanOrEqual": "6.18.*",
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"status": "unaffected"
},
{
"version": "7.2.13",
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},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {},
"references": [
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{
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{
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}