GHSA-97X5-WJV7-8W72
Vulnerability from github – Published: 2025-06-18 12:30 – Updated: 2025-12-17 21:30In the Linux kernel, the following vulnerability has been resolved:
dm cache: prevent BUG_ON by blocking retries on failed device resumes
A cache device failing to resume due to mapping errors should not be retried, as the failure leaves a partially initialized policy object. Repeating the resume operation risks triggering BUG_ON when reloading cache mappings into the incomplete policy object.
Reproduce steps:
- create a cache metadata consisting of 512 or more cache blocks, with some mappings stored in the first array block of the mapping array. Here we use cache_restore v1.0 to build the metadata.
cat <> cmeta.xml EOF dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" cache_restore -i cmeta.xml -o /dev/mapper/cmeta --metadata-version=2 dmsetup remove cmeta
- wipe the second array block of the mapping array to simulate data degradations.
mapping_root=$(dd if=/dev/sdc bs=1c count=8 skip=192 \ 2>/dev/null | hexdump -e '1/8 "%u\n"') ablock=$(dd if=/dev/sdc bs=1c count=8 skip=$((4096*mapping_root+2056)) \ 2>/dev/null | hexdump -e '1/8 "%u\n"') dd if=/dev/zero of=/dev/sdc bs=4k count=1 seek=$ablock
- try bringing up the cache device. The resume is expected to fail due to the broken array block.
dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 65536 linear /dev/sdc 8192" dmsetup create corig --table "0 524288 linear /dev/sdc 262144" dmsetup create cache --notable dmsetup load cache --table "0 524288 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" dmsetup resume cache
- try resuming the cache again. An unexpected BUG_ON is triggered while loading cache mappings.
dmsetup resume cache
Kernel logs:
(snip) ------------[ cut here ]------------ kernel BUG at drivers/md/dm-cache-policy-smq.c:752! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 0 UID: 0 PID: 332 Comm: dmsetup Not tainted 6.13.4 #3 RIP: 0010:smq_load_mapping+0x3e5/0x570
Fix by disallowing resume operations for devices that failed the initial attempt.
{
"affected": [],
"aliases": [
"CVE-2025-38066"
],
"database_specific": {
"cwe_ids": [
"CWE-617"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-06-18T10:15:39Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm cache: prevent BUG_ON by blocking retries on failed device resumes\n\nA cache device failing to resume due to mapping errors should not be\nretried, as the failure leaves a partially initialized policy object.\nRepeating the resume operation risks triggering BUG_ON when reloading\ncache mappings into the incomplete policy object.\n\nReproduce steps:\n\n1. create a cache metadata consisting of 512 or more cache blocks,\n with some mappings stored in the first array block of the mapping\n array. Here we use cache_restore v1.0 to build the metadata.\n\ncat \u003c\u003cEOF \u003e\u003e cmeta.xml\n\u003csuperblock uuid=\"\" block_size=\"128\" nr_cache_blocks=\"512\" \\\npolicy=\"smq\" hint_width=\"4\"\u003e\n \u003cmappings\u003e\n \u003cmapping cache_block=\"0\" origin_block=\"0\" dirty=\"false\"/\u003e\n \u003c/mappings\u003e\n\u003c/superblock\u003e\nEOF\ndmsetup create cmeta --table \"0 8192 linear /dev/sdc 0\"\ncache_restore -i cmeta.xml -o /dev/mapper/cmeta --metadata-version=2\ndmsetup remove cmeta\n\n2. wipe the second array block of the mapping array to simulate\n data degradations.\n\nmapping_root=$(dd if=/dev/sdc bs=1c count=8 skip=192 \\\n2\u003e/dev/null | hexdump -e \u00271/8 \"%u\\n\"\u0027)\nablock=$(dd if=/dev/sdc bs=1c count=8 skip=$((4096*mapping_root+2056)) \\\n2\u003e/dev/null | hexdump -e \u00271/8 \"%u\\n\"\u0027)\ndd if=/dev/zero of=/dev/sdc bs=4k count=1 seek=$ablock\n\n3. try bringing up the cache device. The resume is expected to fail\n due to the broken array block.\n\ndmsetup create cmeta --table \"0 8192 linear /dev/sdc 0\"\ndmsetup create cdata --table \"0 65536 linear /dev/sdc 8192\"\ndmsetup create corig --table \"0 524288 linear /dev/sdc 262144\"\ndmsetup create cache --notable\ndmsetup load cache --table \"0 524288 cache /dev/mapper/cmeta \\\n/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0\"\ndmsetup resume cache\n\n4. try resuming the cache again. An unexpected BUG_ON is triggered\n while loading cache mappings.\n\ndmsetup resume cache\n\nKernel logs:\n\n(snip)\n------------[ cut here ]------------\nkernel BUG at drivers/md/dm-cache-policy-smq.c:752!\nOops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI\nCPU: 0 UID: 0 PID: 332 Comm: dmsetup Not tainted 6.13.4 #3\nRIP: 0010:smq_load_mapping+0x3e5/0x570\n\nFix by disallowing resume operations for devices that failed the\ninitial attempt.",
"id": "GHSA-97x5-wjv7-8w72",
"modified": "2025-12-17T21:30:31Z",
"published": "2025-06-18T12:30:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38066"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/00586b78eeb7c626a14ca13453a1631f88a7cf36"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/025c8f477625eb39006ded650e7d027bcfb20e79"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3986ef4a9b6a0d9c28bc325d8713beba5e67586f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5da692e2262b8f81993baa9592f57d12c2703dea"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c5356a5e80442131e2714d0d26bb110590e4e568"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c614584c2a66b538f469089ac089457a34590c14"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cc80a5cc520939d0a7d071cc4ae4b3c55ef171d0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f3128e3074e8af565cc6a66fe3384a56df87f803"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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