{"id":"CVE-2026-98986","summary":"namespace: remove the fsnotify marks of a mount namespace in process context","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: remove the fsnotify marks of a mount namespace in process context\n\nmnt_ns_release() drops the last passive reference of a mount namespace\nand removes its fanotify marks via fsnotify_mntns_delete(). That takes\nthe mutex of every group with a mark on the namespace and the spinlock\nof the connector. Fine from process context. But mnt_ns_tree_remove()\nhands the reference the namespace was allocated with to call_rcu() and\nso the marks are removed from the RCU softirq:\n\n  BUG: sleeping function called from invalid context at kernel/locking/mutex.c:623\n  in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 0, name: swapper/3\n   __mutex_lock+0x113/0x24b0\n   fsnotify_destroy_marks+0x11b/0x3d0\n   mnt_ns_release_rcu+0x57/0xa0\n   rcu_core+0x6b6/0x1e40\n\nand lockdep complains about the connector lock being taken from softirq\ncontext. A fanotify group with a FAN_MARK_MNTNS mark on the mount\nnamespace of another task is all that's needed. Root in a user\nnamespace can do that for a mount namespace it owns. The task exits and\nthe namespace is freed with the mark still on it.\n\nRemove the marks in free_mnt_ns() before the namespace is handed to RCU.\nThat runs in process context once the last active reference is gone. A\nmark is added through a file descriptor to the namespace which holds an\nactive reference so no mark can show up after that.","modified":"2026-10-25T02:47:28.638026604Z","published":"2026-10-23T12:20:04.966Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98986.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1a116222acdcc1bc1a8350727ae6f28907d44594"},{"type":"WEB","url":"https://git.kernel.org/stable/c/888363d74c3b5d32e2accf217add70f8b38e0e2b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9e820a6becdd955a04adbedfd767253a47eedd9e"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98986.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98986"},{"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":"bf630c40164162ba1d3933c2f5e3397d083e0948"},{"fixed":"888363d74c3b5d32e2accf217add70f8b38e0e2b"},{"fixed":"9e820a6becdd955a04adbedfd767253a47eedd9e"},{"fixed":"1a116222acdcc1bc1a8350727ae6f28907d44594"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-98986.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.15.0"},{"fixed":"6.18.57"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-98986.json"}}],"schema_version":"1.9.2"}