{"id":"DEBIAN-CVE-2026-64142","details":"In the Linux kernel, the following vulnerability has been resolved:  ksmbd: close durable scavenger races against m_fp_list lookups  ksmbd_durable_scavenger() has two related races against any walker that iterates f_ci-\u003em_fp_list, including ksmbd_lookup_fd_inode() (used by ksmbd_vfs_rename) and the share-mode checks in fs/smb/server/smb_common.c.  (1) fp-\u003enode list-head reuse.  Durable-preserved handles can remain linked on f_ci-\u003em_fp_list after session teardown so share-mode checks still see them while the handle is reconnectable.  The scavenger collected expired handles by adding fp-\u003enode to a local scavenger_list after removing them from the global durable idr. Because fp-\u003enode is the same list_head used by m_fp_list, list_add(&fp-\u003enode, &scavenger_list) overwrites the m_fp_list links and corrupts both lists.  CONFIG_DEBUG_LIST can report this on the share-mode walk path.  (2) Refcount race against m_fp_list walkers.  The scavenger qualifies an expired durable handle with atomic_read(&fp-\u003erefcount) \u003e 1 and fp-\u003econn under global_ft.lock, removes fp from global_ft, then drops global_ft.lock before unlinking fp from m_fp_list and freeing it. During that gap fp is still linked on m_fp_list with f_state == FP_INITED.  ksmbd_lookup_fd_inode() under m_lock read calls ksmbd_fp_get() (atomic_inc_not_zero on refcount that is still 1) and takes a live reference; the scavenger then unlinks and frees fp while the holder owns a reference, leading to UAF on the holder's subsequent ksmbd_fd_put() and on any field reads performed by a concurrent share-mode walker that iterates m_fp_list without taking ksmbd_fp_get() (smb_check_perm_dleases-like paths).  Fix both:    * Stop reusing fp-\u003enode as a scavenger-private list node.  Remove     one expired handle from global_ft under global_ft.lock, take an     explicit transient reference, drop the lock, unlink fp-\u003enode     from m_fp_list under f_ci-\u003em_lock, then drop both the durable     lifetime and transient references with atomic_sub_and_test(2,     &fp-\u003erefcount).  If the scavenger is the last putter the close     runs there; otherwise an in-flight holder that already raced     through the m_fp_list lookup owns the final close via its     ksmbd_fd_put() path.  The one-at-a-time disposal can rescan the     durable idr when multiple handles expire in the same pass, but     durable scavenging is a background expiration path and the final     full scan recomputes min_timeout before the next wait.    * Clear fp-\u003epersistent_id inside __ksmbd_remove_durable_fd() right     after idr_remove(), so a delayed final close from a holder that     snatched fp does not re-issue idr_remove() on a persistent id     that idr_alloc_cyclic() in ksmbd_open_durable_fd() may have     already handed out to a brand-new durable handle.    * Bypass the per-conn open_files_count decrement in     __put_fd_final() when fp is detached from any session table     (fp-\u003econn cleared by session_fd_check() at durable preserve --     paired with the volatile_id clear at unpublish, so checking     fp-\u003econn alone is sufficient).  The walker that owns the final     close runs from an unrelated work-\u003econn whose     stats.open_files_count never tracked this durable fp; without     this guard the holder would underflow that unrelated counter.  The two races are folded into one patch because patch (1) alone cleans up the corrupted list but leaves a deterministic UAF window for m_fp_list walkers that the transient-reference and persistent_id discipline in (2) close; bisecting onto an intermediate state would land on a UAF that pre-patch chaos merely made less reproducible.  Validation:   * CONFIG_DEBUG_LIST coverage for the list_head reuse path.   * KASAN-enabled direct SMB2 durable-handle coverage that exercised     ksmbd_durable_scavenger() and non-NULL ksmbd_lookup_fd_inode()     returns while durable handles expired under concurrent rename     lookups, with no KASAN, UAF, list-corruption, ODEBUG, or WARNING     reports. ---truncated---","modified":"2026-08-27T23:06:18.490893898Z","published":"2026-07-19T16:17:56.103Z","upstream":["CVE-2026-64142"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-64142"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.94-1"}]}],"versions":["6.12.38-1","6.12.41-1","6.12.43-1","6.12.43-1~bpo12+1","6.12.48-1","6.12.57-1","6.12.57-1~bpo12+1","6.12.63-1","6.12.63-1~bpo12+1","6.12.69-1","6.12.69-1~bpo12+1","6.12.73-1","6.12.73-1~bpo12+1","6.12.74-1","6.12.74-2","6.12.74-2~bpo12+1","6.12.85-1","6.12.85-1~bpo12+1","6.12.86-1","6.12.86-1~bpo12+1","6.12.88-1","6.12.88-1~bpo12+1","6.12.90-1","6.12.90-1~bpo12+1","6.12.90-2","6.12.90-2~bpo12+1","6.12.94-1~bpo12+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-64142.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"7.0.12-1"}]}],"versions":["6.12.100-1","6.12.101-1","6.12.105-1","6.12.38-1","6.12.41-1","6.12.43-1","6.12.43-1~bpo12+1","6.12.48-1","6.12.57-1","6.12.57-1~bpo12+1","6.12.63-1","6.12.63-1~bpo12+1","6.12.69-1","6.12.69-1~bpo12+1","6.12.73-1","6.12.73-1~bpo12+1","6.12.74-1","6.12.74-2","6.12.74-2~bpo12+1","6.12.85-1","6.12.85-1~bpo12+1","6.12.86-1","6.12.86-1~bpo12+1","6.12.88-1","6.12.88-1~bpo12+1","6.12.90-1","6.12.90-1~bpo12+1","6.12.90-2","6.12.90-2~bpo12+1","6.12.94-1","6.12.94-1~bpo12+1","6.12.95-1","6.12.95-1~bpo12+1","6.12.96-1","6.13.10-1~exp1","6.13.11-1~exp1","6.13.2-1~exp1","6.13.3-1~exp1","6.13.4-1~exp1","6.13.5-1~exp1","6.13.6-1~exp1","6.13.7-1~exp1","6.13.8-1~exp1","6.13.9-1~exp1","6.13~rc6-1~exp1","6.13~rc7-1~exp1","6.14.3-1~exp1","6.14.5-1~exp1","6.14.6-1~exp1","6.15-1~exp1","6.15.1-1~exp1","6.15.2-1~exp1","6.15.3-1~exp1","6.15.4-1~exp1","6.15.5-1~exp1","6.15.6-1~exp1","6.15~rc7-1~exp1","6.16-1~exp1","6.16.1-1~exp1","6.16.10-1","6.16.11-1","6.16.12-1","6.16.12-1~bpo13+1","6.16.12-2","6.16.3-1","6.16.3-1~bpo13+1","6.16.5-1","6.16.6-1","6.16.7-1","6.16.8-1","6.16.9-1","6.16~rc7-1~exp1","6.17.10-1","6.17.11-1","6.17.12-1","6.17.13-1","6.17.13-1~bpo13+1","6.17.2-1~exp1","6.17.5-1~exp1","6.17.6-1","6.17.7-1","6.17.7-2","6.17.8-1","6.17.8-1~bpo13+1","6.17.9-1","6.18.1-1~exp1","6.18.10-1","6.18.12-1","6.18.12-1~bpo13+1","6.18.13-1","6.18.14-1","6.18.15-1","6.18.15-1~bpo13+1","6.18.2-1~exp1","6.18.3-1","6.18.5-1","6.18.5-1~bpo13+1","6.18.8-1","6.18.9-1","6.18.9-1~bpo13+1","6.18~rc4-1~exp1","6.18~rc4-1~exp2","6.18~rc5-1~exp1","6.18~rc6-1~exp1","6.18~rc7-1~exp1","6.19-1~exp1","6.19.10-1","6.19.10-1~bpo13+1","6.19.11-1","6.19.11-1~bpo13+1","6.19.12-1","6.19.13-1","6.19.13-1~bpo13+1","6.19.14-1","6.19.14-1~bpo13+1","6.19.2-1~exp1","6.19.3-1~exp1","6.19.4-1~exp1","6.19.5-1~exp1","6.19.6-1","6.19.6-2","6.19.6-2~bpo13+1","6.19.8-1","6.19.8-1~bpo13+1","6.19~rc4-1~exp1","6.19~rc5-1~exp1","6.19~rc6-1~exp1","6.19~rc7-1~exp1","6.19~rc8-1~exp1","7.0-1~exp1","7.0.1-1~exp1","7.0.10-1","7.0.10-1~bpo13+1","7.0.3-1","7.0.4-1","7.0.4-1~bpo13+1","7.0.7-1","7.0.7-1~bpo13+1","7.0.9-1","7.0.9-1~bpo13+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-64142.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}