{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-21664", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.732Z", "datePublished": "2025-01-21T12:18:19.015Z", "dateUpdated": "2026-08-05T11:53:29.038Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:53:29.038Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm thin: make get_first_thin use rcu-safe list first function\n\nThe documentation in rculist.h explains the absence of list_empty_rcu()\nand cautions programmers against relying on a list_empty() ->\nlist_first() sequence in RCU safe code. This is because each of these\nfunctions performs its own READ_ONCE() of the list head. This can lead\nto a situation where the list_empty() sees a valid list entry, but the\nsubsequent list_first() sees a different view of list head state after a\nmodification.\n\nIn the case of dm-thin, this author had a production box crash from a GP\nfault in the process_deferred_bios path. This function saw a valid list\nhead in get_first_thin() but when it subsequently dereferenced that and\nturned it into a thin_c, it got the inside of the struct pool, since the\nlist was now empty and referring to itself. The kernel on which this\noccurred printed both a warning about a refcount_t being saturated, and\na UBSAN error for an out-of-bounds cpuid access in the queued spinlock,\nprior to the fault itself. When the resulting kdump was examined, it\nwas possible to see another thread patiently waiting in thin_dtr's\nsynchronize_rcu.\n\nThe thin_dtr call managed to pull the thin_c out of the active thins\nlist (and have it be the last entry in the active_thins list) at just\nthe wrong moment which lead to this crash.\n\nFortunately, the fix here is straight forward. Switch get_first_thin()\nfunction to use list_first_or_null_rcu() which performs just a single\nREAD_ONCE() and returns NULL if the list is already empty.\n\nThis was run against the devicemapper test suite's thin-provisioning\nsuites for delete and suspend and no regressions were observed." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable code is the dm-thin pool worker, reached via block I/O to a thin device and via DM device teardown — both require local access to the machine (device file / ioctl), with no network-facing path.\nAC:L - The attacker drives one side of the race continuously (unbounded I/O to the thin device keeps process_deferred_bios re-running) and the removal side is repeatable in a loop, so attempts are unlimited; the commit reports the race firing spontaneously on a production box with no attacker at all.\nPR:L - An unprivileged user with access to a thin volume (container guest, dm device with group/ACL access) supplies the malicious half of the race by flooding deferred bios, while the thin-device teardown is routine automation on LVM-thin/container-storage hosts; with deferred remove armed, an unprivileged holder of the device even triggers thin_dtr directly via close().\nUI:N - No victim action is required — thin volume teardown happens automatically under LVM/container orchestration, and the pool worker runs on its own periodic waker plus attacker-generated I/O.\nS:U - The corruption is confined to kernel memory within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The type confusion makes the worker treat a kernel text address as a struct pool and read through it, and the garbage qspinlock value causes out-of-bounds per-CPU array indexing (the reported UBSAN OOB access), giving wild out-of-bounds reads that can be leveraged for disclosure.\nI:H - The bogus thin_c overlays struct pool's function-pointer tail, so refcount_inc() and spin_lock_irq() write over live function pointers and list_splice_init() writes through wild list heads — memory corruption of indirect-call targets that is exploitable for control-flow hijack.\nA:H - The bug produced a confirmed general-protection fault in process_deferred_bios on a production system, panicking the kernel and taking down all storage served by the thin pool." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/md/dm-thin.c" ], "versions": [ { "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe", "lessThan": "ec037fe8c0d0f6140e3d8a49c7b29cb5582160b8", "status": "affected", "versionType": "git" }, { "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe", "lessThan": "cd30a3960433ec2db94b3689752fa3c5df44d649", "status": "affected", "versionType": "git" }, { "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe", "lessThan": "802666a40c71a23542c43a3f87e3a2d0f4e8fe45", "status": "affected", "versionType": "git" }, { "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe", "lessThan": "12771050b6d059eea096993bf2001da9da9fddff", "status": "affected", "versionType": "git" }, { "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe", "lessThan": "6b305e98de0d225ccebfb225730a9f560d28ecb0", "status": "affected", "versionType": "git" }, { "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe", "lessThan": "cbd0d5ecfa390ac29c5380200147d09c381b2ac6", "status": "affected", "versionType": "git" }, { "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe", "lessThan": "80f130bfad1dab93b95683fc39b87235682b8f72", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/md/dm-thin.c" ], "versions": [ { "version": "3.15", "status": "affected" }, { "version": "0", "lessThan": "3.15", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.290", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.234", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.177", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.125", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.72", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.10", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "5.4.290" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "5.10.234" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "5.15.177" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "6.1.125" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "6.6.72" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "6.12.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.15", "versionEndExcluding": "6.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/ec037fe8c0d0f6140e3d8a49c7b29cb5582160b8" }, { "url": "https://git.kernel.org/stable/c/cd30a3960433ec2db94b3689752fa3c5df44d649" }, { "url": "https://git.kernel.org/stable/c/802666a40c71a23542c43a3f87e3a2d0f4e8fe45" }, { "url": "https://git.kernel.org/stable/c/12771050b6d059eea096993bf2001da9da9fddff" }, { "url": "https://git.kernel.org/stable/c/6b305e98de0d225ccebfb225730a9f560d28ecb0" }, { "url": "https://git.kernel.org/stable/c/cbd0d5ecfa390ac29c5380200147d09c381b2ac6" }, { "url": "https://git.kernel.org/stable/c/80f130bfad1dab93b95683fc39b87235682b8f72" } ], "title": "dm thin: make get_first_thin use rcu-safe list first function", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html" }, { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:58:40.356Z" } }, { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-05-12T12:03:06.963Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 TM MFP - GNU/Linux subsystem", "versions": [ { "status": "affected", "version": "0", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" } ], "references": [ { "url": "https://cert-portal.siemens.com/productcert/html/ssa-265688.html" } ] } ] } }