{"id":"CVE-2026-98986","title":"namespace: remove the fsnotify marks of a mount namespace in process context","summary":"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 fan…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= bf630c40164162ba1d3933c2f5e3397d083e0948 < 888363d74c3b5d32e2accf217add70f8b38e0e2b","Linux >= bf630c40164162ba1d3933c2f5e3397d083e0948 < 9e820a6becdd955a04adbedfd767253a47eedd9e","Linux >= bf630c40164162ba1d3933c2f5e3397d083e0948 < 1a116222acdcc1bc1a8350727ae6f28907d44594","Linux 6.15"],"published":"2026-10-23","updated":"2026-10-23","sourceUpdated":"2026-10-23T12:20:04.966Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98986","references":[{"url":"https://git.kernel.org/stable/c/888363d74c3b5d32e2accf217add70f8b38e0e2b"},{"url":"https://git.kernel.org/stable/c/9e820a6becdd955a04adbedfd767253a47eedd9e"},{"url":"https://git.kernel.org/stable/c/1a116222acdcc1bc1a8350727ae6f28907d44594"}],"tags":["cve.org"],"ingestedAt":"2026-10-23T13:24:55.547Z","slug":"CVE-2026-98986","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= bf630c40164162ba1d3933c2f5e3397d083e0948 < 888363d74c3b5d32e2accf217add70f8b38e0e2b`\n- `Linux >= bf630c40164162ba1d3933c2f5e3397d083e0948 < 9e820a6becdd955a04adbedfd767253a47eedd9e`\n- `Linux >= bf630c40164162ba1d3933c2f5e3397d083e0948 < 1a116222acdcc1bc1a8350727ae6f28907d44594`\n- `Linux 6.15`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}