{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  smb: smbdirect: release pending child sockets outside the handler lock  smbdirect_socket_destroy() releases the listener's pending/ready child sockets while still holding the listener's handler lock, the \u0026id_priv-\u003ehandler_mutex taken via rdma_lock_handler(), not sc-\u003elisten.lock, and before the listener's own rdma_destroy_id(). That ordering has one real consequence and one cosmetic one.  The real one: smbdirect_socket_release() drops the child's last reference, which destroys the child's cm_id.  Doing that before the listener's rdma_destroy_id() lets _cma_cancel_listens(), running from the listener's _destroy_id(), walk an already freed child id_priv, which KASAN catches as a slab-use-after-free during listener shutdown:  [ 4758.909130] BUG: KASAN: slab-use-after-free in __mutex_lock+0x1469/0x1560 [ 4758.911450] Read of size 1 at addr ffff88821c381db4 by task ksmbd.control/1652 [ 4758.913262] Call Trace: [ 4758.913267]  \u003cTASK\u003e [ 4758.913299]  __mutex_lock+0x1469/0x1560 [ 4758.913408]  _cma_cancel_listens+0x312/0x3b0 [ 4758.913413]  _destroy_id+0x363/0xee0 [ 4758.913417]  smbdirect_socket_destroy_sync+0x17d5/0x2440 [ 4758.913443]  smbdirect_socket_release+0x124/0x230 [ 4758.913451]  ksmbd_rdma_stop_listening+0x9f/0x190 [ 4758.913457]  ksmbd_conn_transport_destroy+0x65/0x3c0 [ 4758.913463]  kill_server_store+0x1fb/0x2b0 [ 4758.913501]  kernfs_fop_write_iter+0x349/0x4d0 [ 4758.913507]  vfs_write+0x5e7/0xc70 [ 4758.913528]  ksys_write+0x12a/0x210 [ 4758.913541]  do_syscall_64+0x135/0x460 [ 4758.913555]  entry_SYSCALL_64_after_hwframe+0x77/0x7f  The cosmetic one: releasing a child recurses into smbdirect_socket_destroy(), which takes the child's own rdma_lock_handler() lock nested under the listener's.  The listener's and the child's cm_id are always different instances, so this cannot deadlock for real; the CM core itself nests a new connection id's handler_mutex under the listening id's in cma_ib_req_handler().  But lockdep only sees one lock class, reports possible recursive locking, and then disables itself, hiding real locking bugs for the rest of the run:  [ 2424.579653] WARNING: possible recursive locking detected [ 2424.581180] 7.1.0-next-20260623+ #89 Not tainted [ 2424.582548] -------------------------------------------- [ 2424.584500] ksmbd.control/8854 is trying to acquire lock: [ 2424.586817] ffff888102303c20 (\u0026id_priv-\u003ehandler_mutex){+.+.}-{4:4}, at: smbdirect_socket_destroy_sync+0xc39/0x2440 [ 2424.590590] [ 2424.590590] but task is already holding lock: [ 2424.591601] ffff888102046c20 (\u0026id_priv-\u003ehandler_mutex){+.+.}-{4:4}, at: smbdirect_socket_destroy_sync+0xc39/0x2440 [ 2424.594178] [ 2424.594178] other info that might help us debug this: [ 2424.596634]  Possible unsafe locking scenario: [ 2424.596634] [ 2424.598841]        CPU0 [ 2424.599765]        ---- [ 2424.600695]   lock(\u0026id_priv-\u003ehandler_mutex); [ 2424.601836]   lock(\u0026id_priv-\u003ehandler_mutex); [ 2424.602590] [ 2424.602590]  *** DEADLOCK *** [ 2424.602590] [ 2424.604512]  May be due to missing lock nesting notation  Splice the pending/ready children onto a local list under the listener's listen.lock, while the handler lock is held so a concurrent CM CONNECT_REQUEST cannot add more, but defer the actual smbdirect_socket_release() calls until after the listener's cm_id has been destroyed and its handler lock dropped.  The children are independent sockets whose teardown needs neither the listener's handler lock nor its cm_id.  Found with ksmbdzzer [2], a KSMBD fuzzer that drives libFuzzer with a kcov-dataflow [1] coverage vector: it folds each instrumented comparison/argument's runtime operand value together with its PC (the default arm mixes them as pc⊕val) so that a new operand value at a known site counts as new coverage.  [1] https://lwn.net/Articles/1077606/ [2] https://github.com/yskzalloc/kcov-dataflow",
  "id": "DEBIAN-CVE-2026-90171",
  "modified": "2026-09-18T04:47:32.514334536Z",
  "published": "2026-09-17T17:17:10.650Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-90171"
    }
  ],
  "upstream": [
    "CVE-2026-90171"
  ]
}