{"cve":"CVE-2025-38066","nvd":{"published":"2025-06-18T10:15:39.620","modified":"2026-06-17T09:15:59.207","status":"Analyzed","description":"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 <<EOF >> cmeta.xml\n<superblock uuid=\"\" block_size=\"128\" nr_cache_blocks=\"512\" \\\npolicy=\"smq\" hint_width=\"4\">\n  <mappings>\n    <mapping cache_block=\"0\" origin_block=\"0\" dirty=\"false\"/>\n  </mappings>\n</superblock>\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=$(dd if=/dev/sdc bs=1c count=8 skip=192 \\\n2>/dev/null | hexdump -e '1/8 \"%u\\n\"')\nablock=$(dd if=/dev/sdc bs=1c count=8 skip=$((4096*mapping_root+2056)) \\\n2>/dev/null | hexdump -e '1/8 \"%u\\n\"')\ndd if=/dev/zero of=/dev/sdc bs=4k count=1 seek=$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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-617"],"references":["https://git.kernel.org/stable/c/00586b78eeb7c626a14ca13453a1631f88a7cf36","https://git.kernel.org/stable/c/025c8f477625eb39006ded650e7d027bcfb20e79","https://git.kernel.org/stable/c/3986ef4a9b6a0d9c28bc325d8713beba5e67586f","https://git.kernel.org/stable/c/5da692e2262b8f81993baa9592f57d12c2703dea","https://git.kernel.org/stable/c/c5356a5e80442131e2714d0d26bb110590e4e568"],"products":["debian:debian_linux","linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:03:23.287444849+00:00"},"epss":{"cve":"CVE-2025-38066","score":0.00199,"percentile":0.09715,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}