{ "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-2026-89675", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-89675", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-09-11T19:45:59.635Z", "updatedAt": "2026-10-19T08:50:48.585Z", "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": "nfsd: fix UAF in async copy cancel and shutdown", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix UAF in async copy cancel and shutdown\n\nAn async copy could be freed or used after free while a teardown caller\n(OFFLOAD_CANCEL, nfsd4_shutdown_copy, nfsd4_cancel_copy_by_sb) raced the\ncopy kthread:\n\n - find_async_copy() bumped copy->refcount but left the copy on\n clp->async_copies, so the reaper's cleanup_async_copy() could run\n release_copy_files() concurrently with a cancel/shutdown caller. Both\n put and NULL nf_src/nf_dst without a common lock, double-putting the\n nfsd_file and freeing it early.\n\n - nfsd4_do_async_copy() set NFSD4_COPY_F_STOPPED before its final uses\n of the copy (nfsd_update_cmtime_attr() on copy->nf_dst,\n nfsd4_send_cb_offload()). nfsd4_stop_copy() treats a set STOPPED bit\n as \"kthread done, skip kthread_stop()\", so a teardown caller ran\n release_copy_files() -- which puts and NULLs nf_dst -- while the\n kthread still dereferenced it (NULL/UAF).\n\n - copy->copy_task was never pinned. The one-shot kthread self-reaps on\n return, so kthread_stop()'s get_task_struct() could touch a freed\n task_struct.\n\n - co_cb is embedded in the copy, but nfsd4_send_cb_offload() held a\n reference only on the client, so a concurrent teardown could free\n the copy while the CB_OFFLOAD callback was in flight.\n\nFix the teardown lifetime as a whole:\n\n - find_async_copy() unlinks the copy (clear cp_clp, list_del_init)\n under async_lock; the cancel, shutdown, and sb-cancel paths drop the\n list-membership reference via nfs4_put_copy() after nfsd4_stop_copy().\n Drop the now-redundant list_del fixup from cleanup_async_copy().\n\n - Because unlinking hides the copy from the reaper, its\n cleanup_async_copy() can no longer remove the copy's s2s_cp_stateids\n entry; the cancel/shutdown/sb-cancel paths now call\n nfs4_free_copy_state() themselves (while cp_clp is still valid) so\n the entry does not dangle at freed memory for the laundromat and\n manage_cpntf_state() to dereference.\n\n - Give the kthread its own reference, taken in nfsd4_copy() before\n wake_up_process() and dropped at the end of nfsd4_do_async_copy();\n call wake_up_process() before list_add().\n\n - Pin the task_struct with get_task_struct() in nfsd4_copy(), released\n in nfs4_put_copy(), so kthread_stop() is safe whenever the kthread\n exits. Set NFSD4_COPY_F_STOPPED only in nfsd4_stop_copy(), which now\n always kthread_stop()s before release_copy_files(); completion is\n still reported via NFSD4_COPY_F_COMPLETED, so\n nfsd4_has_active_async_copies() is unaffected. Each teardown caller\n removes the copy from clp->async_copies first, so kthread_stop() runs\n exactly once.\n\n - Take a copy reference in nfsd4_send_cb_offload(), dropped in\n nfsd4_cb_offload_release(). The kthread still holds its own reference\n there, so the refcount_inc() cannot race the final free.\n\n - Read cp_clp with smp_load_acquire() to pair with the unordered\n set_bit()/clear_bit() writers (Documentation/atomic_bitops.rst).", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "e0639dc5805a9d4faaa2c07ad98fa853b9529dd3", "status": "affected", "versionType": "git", "lessThan": "9031493ef7369d5c59c4bacc96f0c85965f09a98" }, { "version": "e0639dc5805a9d4faaa2c07ad98fa853b9529dd3", "status": "affected", "versionType": "git", "lessThan": "a385cf5e016b748babf94cc664e43a26e17db117" }, { "version": "e0639dc5805a9d4faaa2c07ad98fa853b9529dd3", "status": "affected", "versionType": "git", "lessThan": "62c0f6eaf050bb9284c1f9cac6ed1770092e6b95" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "4.20", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "4.20" }, { "version": "6.18.51", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.2.4", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.2.*" }, { "version": "7.3", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }