{"id":"CVE-2026-89712","summary":"NFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock\n\nnfsd4_ssc_expire_umount() walks nn-\u003enfsd_ssc_mount_list with\nlist_for_each_entry_safe(ni, tmp, ...).  For each expired entry it\nsets nsui_busy = true, drops nfsd_ssc_lock to run mntput() on the\nsource vfsmount, then reacquires the lock to list_del + kfree the\nentry and continue iterating via the macro's saved tmp pointer.\n\nThe nsui_busy flag protects the current ni from concurrent\nnfsd4_ssc_setup_dul() finders during the lock-drop window, but it\ndoes not pin tmp.  Another nfsd RPC thread that fails its source-\nserver mount and reaches nfsd4_ssc_cancel_dul() will, during that\nsame window, take nfsd_ssc_lock, list_del + kfree its own ssc_umount\nitem, and release the lock.  If that item is the saved tmp of the\nexpire walk, the next iteration dereferences a freed\nnfsd4_ssc_umount_item.\n\nRestart the walk from the head after the mntput() unlock window so\nno saved next pointer survives the lock-drop.  The list is bounded\nby the number of active inter-server source mounts (typically small)\nand the expire delayed-work runs periodically rather than per-IO,\nso the restart is cheap.","modified":"2026-10-28T02:30:39.413119356Z","published":"2026-09-11T19:46:27.018Z","related":["SUSE-SU-2026:24179-1","SUSE-SU-2026:24181-1","SUSE-SU-2026:24182-1","SUSE-SU-2026:24184-1","SUSE-SU-2026:24197-1","SUSE-SU-2026:24235-1","SUSE-SU-2026:24315-1","SUSE-SU-2026:24316-1","SUSE-SU-2026:4640-1","SUSE-SU-2026:4706-1","openSUSE-SU-2026:11880-1","openSUSE-SU-2026:22091-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89712.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/036c1b182f4da65363e79ec0ac276edc6b7296e5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2b59029b8f24a99b5d844af2da3950d39d36eeea"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/60680ae7243b22de3d09be990d8e23bcfc4af837"},{"type":"WEB","url":"https://git.kernel.org/stable/c/659ee3da073164e1e6e40dfcbc26eeed85845f93"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/77de363d9a1c8cd35f20482782c612cda085791a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d9e151fea5ed706c1284adacabd869b0be745db2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89712.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89712"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"a4bc287943f5695209ff36bdc89f17b48d68fae7"},{"fixed":"2b59029b8f24a99b5d844af2da3950d39d36eeea"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"f4e44b393389c77958f7c58bf4415032b4cda15b"},{"fixed":"d9e151fea5ed706c1284adacabd869b0be745db2"},{"fixed":"659ee3da073164e1e6e40dfcbc26eeed85845f93"},{"fixed":"60680ae7243b22de3d09be990d8e23bcfc4af837"},{"fixed":"77de363d9a1c8cd35f20482782c612cda085791a"},{"fixed":"4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8"},{"fixed":"7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9"},{"fixed":"036c1b182f4da65363e79ec0ac276edc6b7296e5"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5.10.220"},{"fixed":"5.10.270"}]}],"versions":["v5.10.269","v5.10.268","v5.10.267","v5.10.266","v5.10.265","v5.10.264","v5.10.263","v5.10.262","v5.10.261","v5.10.260","v5.10.259","v5.10.258","v5.10.257","v5.10.256","v5.10.255","v5.10.254","v5.10.253","v5.10.252","v5.10.251","v5.10.250","v5.10.249","v5.10.248","v5.10.247","v5.10.246","v5.10.245","v5.10.244","v5.10.243","v5.10.242","v5.10.241","v5.10.240","v5.10.239","v5.10.238","v5.10.237","v5.10.236","v5.10.235","v5.10.234","v5.10.233","v5.10.232","v5.10.231","v5.10.230","v5.10.229","v5.10.228","v5.10.227","v5.10.226","v5.10.225","v5.10.224","v5.10.223","v5.10.222","v5.10.221","v5.10.220"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89712.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.10.270"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.221"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.14.0"},{"fixed":"6.1.188"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.6.157"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.12.109"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.18.50"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89712.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}