GHSA-4J2M-GFQM-629P
Vulnerability from github – Published: 2026-06-24 18:32 – Updated: 2026-06-28 09:31In the Linux kernel, the following vulnerability has been resolved:
dm cache policy smq: fix missing locks in invalidating cache blocks
In passthrough mode, the policy invalidate_mapping operation is called simultaneously from multiple workers, thus it should be protected by a lock. Otherwise, we might end up with data races on the allocated blocks counter, or even use-after-free issues with internal data structures when doing concurrent writes.
Note that the existing FIXME in smq_invalidate_mapping() doesn't affect passthrough mode since migration tasks don't exist there, but would need attention if supporting fast device shrinking via suspend/resume without target reloading.
Reproduce steps:
- Create a cache device consisting of 1024 cache entries
dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 131072 linear /dev/sdc 8192" dmsetup create corig --table "0 262144 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"
- Populate the cache, and record the number of cached blocks
fio --name=populate --filename=/dev/mapper/cache --rw=randwrite --bs=4k \ --size=64m --direct=1 nr_cached=$(dmsetup status cache | awk '{split($7, a, "/"); print a[1]}')
- Reload the cache into passthrough mode
dmsetup suspend cache dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0" dmsetup resume cache
- Write to the passthrough cache. By setting multiple jobs with I/O size equal to the cache block size, cache blocks are invalidated concurrently from different workers.
fio --filename=/dev/mapper/cache --name=test --rw=randwrite --bs=64k \ --direct=1 --numjobs=2 --randrepeat=0 --size=64m
- Check if demoted matches cached block count. These numbers should match but may differ due to the data race.
nr_demoted=$(dmsetup status cache | awk '{print $12}') echo "$nr_cached, $nr_demoted"
{
"affected": [],
"aliases": [
"CVE-2026-53062"
],
"database_specific": {
"cwe_ids": [
"CWE-667"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-06-24T17:17:19Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm cache policy smq: fix missing locks in invalidating cache blocks\n\nIn passthrough mode, the policy invalidate_mapping operation is called\nsimultaneously from multiple workers, thus it should be protected by a\nlock. Otherwise, we might end up with data races on the allocated blocks\ncounter, or even use-after-free issues with internal data structures\nwhen doing concurrent writes.\n\nNote that the existing FIXME in smq_invalidate_mapping() doesn\u0027t affect\npassthrough mode since migration tasks don\u0027t exist there, but would need\nattention if supporting fast device shrinking via suspend/resume without\ntarget reloading.\n\nReproduce steps:\n\n1. Create a cache device consisting of 1024 cache entries\n\ndmsetup create cmeta --table \"0 8192 linear /dev/sdc 0\"\ndmsetup create cdata --table \"0 131072 linear /dev/sdc 8192\"\ndmsetup create corig --table \"0 262144 linear /dev/sdc 262144\"\ndd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct\ndmsetup create cache --table \"0 262144 cache /dev/mapper/cmeta \\\n/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0\"\n\n2. Populate the cache, and record the number of cached blocks\n\nfio --name=populate --filename=/dev/mapper/cache --rw=randwrite --bs=4k \\\n--size=64m --direct=1\nnr_cached=$(dmsetup status cache | awk \u0027{split($7, a, \"/\"); print a[1]}\u0027)\n\n3. Reload the cache into passthrough mode\n\ndmsetup suspend cache\ndmsetup reload cache --table \"0 262144 cache /dev/mapper/cmeta \\\n/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0\"\ndmsetup resume cache\n\n4. Write to the passthrough cache. By setting multiple jobs with I/O\n size equal to the cache block size, cache blocks are invalidated\n concurrently from different workers.\n\nfio --filename=/dev/mapper/cache --name=test --rw=randwrite --bs=64k \\\n--direct=1 --numjobs=2 --randrepeat=0 --size=64m\n\n5. Check if demoted matches cached block count. These numbers should\n match but may differ due to the data race.\n\nnr_demoted=$(dmsetup status cache | awk \u0027{print $12}\u0027)\necho \"$nr_cached, $nr_demoted\"",
"id": "GHSA-4j2m-gfqm-629p",
"modified": "2026-06-28T09:31:40Z",
"published": "2026-06-24T18:32:45Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53062"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1b2bec4a7dcf5f00b7a1cbeeec8997841d783513"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2b62d0611c9af14a16bddf22df2612b4f40eb5a1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2d1f7b65f5deedd2e6b09fdc6ea27f8375f24b45"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4991b5a08751e2e82488fb93ae08849b6aea10d9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/93627a29d4b66d4a2def938dfb8610cc80ae454b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9a5fdfb9e57ec3a8ad2b8fce5e5ffa42d53b130e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ac5ee99443891bdb161f5539606a66a1b5e72542"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c348ae47d8e65f06429fa41adce9ad986b696766"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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