{"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":"2025-11-03T20:58:40.356Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2025-05-04T07:18:30.814Z"},"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."}],"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"}}]}}