{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-93100", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-93100", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-09-17T16:11:13.077Z", "updatedAt": "2026-10-21T12:51:53.171Z", "importedAt": "2026-10-24T01:58:35.090Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/resctrl: Prevent use-after-free in rdtgroup_kn_put()\n\nA struct rdtgroup is reference counted via rdtgroup::waitcount. Callers that\nneed the structure to remain valid across a sleep (while waiting on acquiring\nrdtgroup_mutex) take a reference with rdtgroup_kn_get() and release it with\nrdtgroup_kn_put().\n\nThe release path is intended to serve as the fallback freer: if the count\ndrops to zero and the group has already been marked RDT_DELETED,\nrdtgroup_kn_put() frees the structure.\n\nThe bulk teardown paths free_all_child_rdtgrp() and rmdir_all_sub() resulting\nfrom a resctrl directory remove or resctrl fs unmount act as the primary\nfreer: they hold rdtgroup_mutex and free each rdtgroup whose waitcount is\nzero, otherwise they set RDT_DELETED and leave the freeing to the last waiter.\n\nThese two freers race. rdtgroup_kn_put() commits waitcount == 0 with\natomic_dec_and_test() outside rdtgroup_mutex, then reads rdtgroup::flags.\nBetween those two operations a concurrent caller of free_all_child_rdtgrp()\nor rmdir_all_sub() (which holds the mutex) can observe waitcount == 0 via\natomic_read(), call rdtgroup_remove(), and kfree() the structure.\n\nThe subsequent read of rdtgroup::flags in rdtgroup_kn_put() is then\na use-after-free, and the structure may even be freed twice if the freed\nmemory happens to satisfy the RDT_DELETED flag check.\n\nReplace the bare atomic_dec_and_test() with atomic_dec_and_mutex_lock() so\nthat the decrement-to-zero takes rdtgroup_mutex before the count becomes\nglobally visible. The inspection of rdtgroup::flags then runs under the same\nmutex held by the bulk freers, making the two paths mutually exclusive.\n\nThe common case where the count does not reach zero remains lock-free. Defer\nkernfs_unbreak_active_protection() until after the mutex is dropped since\nkernfs active protections functionally wrap rdtgroup_mutex. Remove resource\ngroup, which in turn drops its kernfs reference, after kernfs protection is\nrestored.\n\n [ bp: Split the commit messsages into smaller, easier-parseable paragraphs. ]", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "b8511ccc75c033f6d54188ea4df7bf1e85778740", "status": "affected", "versionType": "git", "lessThan": "971b40e3ca1279ca4917889e0195d33b66d071a4" }, { "version": "b8511ccc75c033f6d54188ea4df7bf1e85778740", "status": "affected", "versionType": "git", "lessThan": "828ff461c136b95d13b8d712c0a7a06a640e313a" }, { "version": "b8511ccc75c033f6d54188ea4df7bf1e85778740", "status": "affected", "versionType": "git", "lessThan": "ae69f936e8ffed553d899ba4c02f8a7461a89e54" }, { "version": "b8511ccc75c033f6d54188ea4df7bf1e85778740", "status": "affected", "versionType": "git", "lessThan": "4c593c62c1499665baebbb41b70e2c9b7e947b86" }, { "version": "b8511ccc75c033f6d54188ea4df7bf1e85778740", "status": "affected", "versionType": "git", "lessThan": "f5bcf539484d2d604c2f2330e09487ea090b21c7" }, { "version": "d20edc0bca5577bab38acb5b190619c922ddebf8", "status": "affected", "versionType": "git" }, { "version": "1b006f8cbde9f3dabdfafe2ff7aa9f831ed5b625", "status": "affected", "versionType": "git" }, { "version": "40300f986e47dbc8f1d02e5080385f5cf9f85f70", "status": "affected", "versionType": "git" }, { "version": "b5a4949897ebada8132d54c93208989482503103", "status": "affected", "versionType": "git" }, { "version": "4.14.170", "status": "affected", "versionType": "semver", "lessThan": "4.15" }, { "version": "4.19.102", "status": "affected", "versionType": "semver", "lessThan": "4.20" }, { "version": "5.4.18", "status": "affected", "versionType": "semver", "lessThan": "5.5" }, { "version": "5.5.2", "status": "affected", "versionType": "semver", "lessThan": "5.6" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "5.6", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "5.6" }, { "version": "6.6.160", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.114", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.52", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.2.6", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.2.*" }, { "version": "7.3", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }