{"id":"CVE-2026-93221","revision":"0a89d6c327524ac293d16e50fbab561d","records":[{"revision":"0a89d6c327524ac293d16e50fbab561d","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-93221","aliases":[],"title":"nfsd: convert nfsd_net boolean flags to unsigned long flags word","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: convert nfsd_net boolean flags to unsigned long flags word\n\nnfsd_net contains several boolean fields that are accessed from\nconcurrent contexts without serialization. In particular,\nnfsd4_end_grace() guards its drain path with a plain bool:\n\n if (nn->grace_ended)\n return;\n nn->grace_ended = true;\n\nThe read and the write are independent, and nothing in struct\nnfsd_net serializes them. At least two contexts can reach this\ncode with no lock held:\n\n laundromat path\n laundry_wq kworker\n nfs4_laundromat()\n nfsd4_end_grace()\n\n RECLAIM_COMPLETE path\n nfsd compound kthread\n nfsd4_reclaim_complete()\n inc_reclaim_complete()\n nfsd4_end_grace()\n\nBoth callers can observe grace_ended == false on different CPUs,\nboth store true, and both proceed into nfsd4_record_grace_done(),\nwhich invokes the active client_tracking_ops->grace_done callback.\nFor tracking ops that drain reclaim_str_hashtbl (legacy_tracking_ops\nvia nfsd4_recdir_purge_old, and the cld v1+ ops via\nnfsd4_cld_grace_done), grace_done calls nfs4_release_reclaim(),\nwhich walks every bucket of reclaim_str_hashtbl with no lock and\ncalls nfs4_remove_reclaim_record() (list_del + kfree) on each\nentry. Two concurrent walkers corrupt the list and double-free\nevery nfs4_client_reclaim. A concurrent nfsd4_find_reclaim_client()\niterating the same bucket reads through freed memory.\n\nA third call site exists in nfs4_state_start_net() on the\nskip_grace startup path, but it runs under nfsd_mutex before any\nclient has connected and before the laundromat's first delayed\nwork fires, so it cannot race with the two callers above.\n\nReplace the scattered boolean fields in nfsd_net with a single\nunsigned long flags word and an enum nfsd_net_flag for the bit\npositions. The grace_ended race is fixed by using\ntest_and_set_bit(), which is atomic on all architectures. The\nremaining flags (grace_end_forced, in_grace, somebody_reclaimed,\ntrack_reclaim_completes, nfsd_net_up, lockd_up) are converted to\nuse test_bit/set_bit/clear_bit for consistency. This avoids\nsub-word cmpxchg issues on architectures like Hexagon that only\nsupport word-sized atomic operations.","state":0,"publishedAt":"2026-09-24T15:10:44.598+00:00","modifiedAt":"2026-10-21T12:52:22.888+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"fs/nfsd/netns.h\",\n \"fs/nfsd/nfs4proc.c\",\n \"fs/nfsd/nfs4recover.c\",\n \"fs/nfsd/nfs4state.c\",\n \"fs/nfsd/nfsctl.c\",\n \"fs/nfsd/nfssvc.c\"\n ],\n \"versions\": [\n {\n \"version\": \"362063a595be959bc08f4163e6405a0266740091\",\n \"lessThan\": \"94b450977c60261903c945419d2df4a464de60c4\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"362063a595be959bc08f4163e6405a0266740091\",\n \"lessThan\": \"faac245ca739b66e96fb7bb43e21df537239a4e5\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"362063a595be959bc08f4163e6405a0266740091\",\n \"lessThan\": \"40bab0da844c142431a6b1cc21b4cf53491dac44\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"362063a595be959bc08f4163e6405a0266740091\",\n \"lessThan\": \"df5922fe09a8131c793ffa86adf204999b0470f8\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"362063a595be959bc08f4163e6405a0266740091\",\n \"lessThan\": \"11a5fe42e1811f793e04ef885b639ea7668f439d\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"fs/nfsd/netns.h\",\n \"fs/nfsd/nfs4proc.c\",\n \"fs/nfsd/nfs4recover.c\",\n \"fs/nfsd/nfs4state.c\",\n \"fs/nfsd/nfsctl.c\",\n \"fs/nfsd/nfssvc.c\"\n ],\n \"versions\": [\n {\n \"version\": \"5.2\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"5.2\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.160\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.114\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.57\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2.4\",\n \"lessThanOrEqual\": \"7.2.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.3\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.1,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/94b450977c60261903c945419d2df4a464de60c4","https://git.kernel.org/stable/c/faac245ca739b66e96fb7bb43e21df537239a4e5","https://git.kernel.org/stable/c/40bab0da844c142431a6b1cc21b4cf53491dac44","https://git.kernel.org/stable/c/df5922fe09a8131c793ffa86adf204999b0470f8","https://git.kernel.org/stable/c/11a5fe42e1811f793e04ef885b639ea7668f439d"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-93221","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-93221","identifiers":["CVE-2026-93221"]},"retained":false,"historicalAffected":[]}],"coverage":[]}