{"id":"CVE-2025-40090","state":"PUBLISHED","title":"ksmbd: fix recursive locking in RPC handle list access","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix recursive locking in RPC handle list access\n\nSince commit 305853cce3794 (\"ksmbd: Fix race condition in RPC handle list\naccess\"), ksmbd_session_rpc_method() attempts to lock sess->rpc_lock.\n\nThis causes hung connections / tasks when a client attempts to open\na named pipe. Using Samba's rpcclient tool:\n\n $ rpcclient //192.168.1.254 -U user%password\n $ rpcclient $> srvinfo\n <connection hung here>\n\nKernel side:\n  \"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\" disables this message.\n  task:kworker/0:0 state:D stack:0 pid:5021 tgid:5021 ppid:2 flags:0x00200000\n  Workqueue: ksmbd-io handle_ksmbd_work\n  Call trace:\n  __schedule from schedule+0x3c/0x58\n  schedule from schedule_preempt_disabled+0xc/0x10\n  schedule_preempt_disabled from rwsem_down_read_slowpath+0x1b0/0x1d8\n  rwsem_down_read_slowpath from down_read+0x28/0x30\n  down_read from ksmbd_session_rpc_method+0x18/0x3c\n  ksmbd_session_rpc_method from ksmbd_rpc_open+0x34/0x68\n  ksmbd_rpc_open from ksmbd_session_rpc_open+0x194/0x228\n  ksmbd_session_rpc_open from create_smb2_pipe+0x8c/0x2c8\n  create_smb2_pipe from smb2_open+0x10c/0x27ac\n  smb2_open from handle_ksmbd_work+0x238/0x3dc\n  handle_ksmbd_work from process_scheduled_works+0x160/0x25c\n  process_scheduled_works from worker_thread+0x16c/0x1e8\n  worker_thread from kthread+0xa8/0xb8\n  kthread from ret_from_fork+0x14/0x38\n  Exception stack(0x8529ffb0 to 0x8529fff8)\n\nThe task deadlocks because the lock is already held:\n  ksmbd_session_rpc_open\n    down_write(&sess->rpc_lock)\n    ksmbd_rpc_open\n      ksmbd_session_rpc_method\n        down_read(&sess->rpc_lock)   <-- deadlock\n\nAdjust ksmbd_session_rpc_method() callers to take the lock when necessary.","publishedAt":"2025-10-30T09:47:58.611Z","updatedAt":"2026-08-05T12:07:42.312Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"69674b029002b1d90b655f014bdf64f404efa54d","status":"affected","lessThan":"5493571f4351f74e11db9943e98a07c56467cf7e","versionType":"git"},{"version":"6b615a8fb3af0baf8126cde3d4fee97d57222ffc","status":"affected","lessThan":"1891abe832cbf5a11039e088766131d0f1642d02","versionType":"git"},{"version":"5cc679ba0f4505936124cd4179ba66bb0a4bd9f3","status":"affected","lessThan":"4602b8cee1481dbb896182e5cb1e8cf12910e9e7","versionType":"git"},{"version":"6bd7e0e55dcea2cf0d391bbc21c2eb069b4be3e1","status":"affected","lessThan":"3412fbd81b46b9cfae013817b61d4bbd27e09e36","versionType":"git"},{"version":"305853cce379407090a73b38c5de5ba748893aee","status":"affected","lessThan":"88f170814fea74911ceab798a43cbd7c5599bed4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/mgmt/user_session.c","fs/smb/server/smb2pdu.c","fs/smb/server/transport_ipc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"6.12.53","status":"affected","lessThan":"6.12.55","versionType":"semver"},{"version":"6.17.3","status":"affected","lessThan":"6.17.5","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/mgmt/user_session.c","fs/smb/server/smb2pdu.c","fs/smb/server/transport_ipc.c"]}],"references":["https://git.kernel.org/stable/c/5493571f4351f74e11db9943e98a07c56467cf7e","https://git.kernel.org/stable/c/1891abe832cbf5a11039e088766131d0f1642d02","https://git.kernel.org/stable/c/4602b8cee1481dbb896182e5cb1e8cf12910e9e7","https://git.kernel.org/stable/c/3412fbd81b46b9cfae013817b61d4bbd27e09e36","https://git.kernel.org/stable/c/88f170814fea74911ceab798a43cbd7c5599bed4"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/40xxx/CVE-2025-40090.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-40090","state":"PUBLISHED","datePublished":"2025-10-30T09:47:58.611Z","dateUpdated":"2026-08-05T12:07:42.312Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:20:57.162Z"},"containers":{"cna":{"title":"ksmbd: fix recursive locking in RPC handle list access","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix recursive locking in RPC handle list access\n\nSince commit 305853cce3794 (\"ksmbd: Fix race condition in RPC handle list\naccess\"), ksmbd_session_rpc_method() attempts to lock sess->rpc_lock.\n\nThis causes hung connections / tasks when a client attempts to open\na named pipe. Using Samba's rpcclient tool:\n\n $ rpcclient //192.168.1.254 -U user%password\n $ rpcclient $> srvinfo\n <connection hung here>\n\nKernel side:\n  \"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\" disables this message.\n  task:kworker/0:0 state:D stack:0 pid:5021 tgid:5021 ppid:2 flags:0x00200000\n  Workqueue: ksmbd-io handle_ksmbd_work\n  Call trace:\n  __schedule from schedule+0x3c/0x58\n  schedule from schedule_preempt_disabled+0xc/0x10\n  schedule_preempt_disabled from rwsem_down_read_slowpath+0x1b0/0x1d8\n  rwsem_down_read_slowpath from down_read+0x28/0x30\n  down_read from ksmbd_session_rpc_method+0x18/0x3c\n  ksmbd_session_rpc_method from ksmbd_rpc_open+0x34/0x68\n  ksmbd_rpc_open from ksmbd_session_rpc_open+0x194/0x228\n  ksmbd_session_rpc_open from create_smb2_pipe+0x8c/0x2c8\n  create_smb2_pipe from smb2_open+0x10c/0x27ac\n  smb2_open from handle_ksmbd_work+0x238/0x3dc\n  handle_ksmbd_work from process_scheduled_works+0x160/0x25c\n  process_scheduled_works from worker_thread+0x16c/0x1e8\n  worker_thread from kthread+0xa8/0xb8\n  kthread from ret_from_fork+0x14/0x38\n  Exception stack(0x8529ffb0 to 0x8529fff8)\n\nThe task deadlocks because the lock is already held:\n  ksmbd_session_rpc_open\n    down_write(&sess->rpc_lock)\n    ksmbd_rpc_open\n      ksmbd_session_rpc_method\n        down_read(&sess->rpc_lock)   <-- deadlock\n\nAdjust ksmbd_session_rpc_method() callers to take the lock when necessary."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"69674b029002b1d90b655f014bdf64f404efa54d","status":"affected","lessThan":"5493571f4351f74e11db9943e98a07c56467cf7e","versionType":"git"},{"version":"6b615a8fb3af0baf8126cde3d4fee97d57222ffc","status":"affected","lessThan":"1891abe832cbf5a11039e088766131d0f1642d02","versionType":"git"},{"version":"5cc679ba0f4505936124cd4179ba66bb0a4bd9f3","status":"affected","lessThan":"4602b8cee1481dbb896182e5cb1e8cf12910e9e7","versionType":"git"},{"version":"6bd7e0e55dcea2cf0d391bbc21c2eb069b4be3e1","status":"affected","lessThan":"3412fbd81b46b9cfae013817b61d4bbd27e09e36","versionType":"git"},{"version":"305853cce379407090a73b38c5de5ba748893aee","status":"affected","lessThan":"88f170814fea74911ceab798a43cbd7c5599bed4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/mgmt/user_session.c","fs/smb/server/smb2pdu.c","fs/smb/server/transport_ipc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"6.12.53","status":"affected","lessThan":"6.12.55","versionType":"semver"},{"version":"6.17.3","status":"affected","lessThan":"6.17.5","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/mgmt/user_session.c","fs/smb/server/smb2pdu.c","fs/smb/server/transport_ipc.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/5493571f4351f74e11db9943e98a07c56467cf7e"},{"url":"https://git.kernel.org/stable/c/1891abe832cbf5a11039e088766131d0f1642d02"},{"url":"https://git.kernel.org/stable/c/4602b8cee1481dbb896182e5cb1e8cf12910e9e7"},{"url":"https://git.kernel.org/stable/c/3412fbd81b46b9cfae013817b61d4bbd27e09e36"},{"url":"https://git.kernel.org/stable/c/88f170814fea74911ceab798a43cbd7c5599bed4"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - ksmbd is the in-kernel SMB server listening on TCP/445, and the deadlock is triggered by a remote client sending an SMB2 CREATE for a named pipe on the IPC$ tree. No local access is needed.\nAC:L - This is an unconditional self-deadlock on a non-recursive rw_semaphore, hit deterministically on the very first named-pipe open — no race to win, no memory layout or timing dependency.\nPR:N - In the guest-mapping configuration common on ksmbd's NAS/embedded targets, ntlm_authenticate() skips NTLM password verification entirely for guest users, so an attacker with no credentials can establish a session, tree-connect to the always-present IPC$ share, and reach create_smb2_pipe().\nUI:N - The attacker triggers the deadlock purely by sending SMB2 protocol messages; no action by any local user or administrator is required.\nS:U - The deadlock affects kernel worker threads and ksmbd's own locks within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:N - The thread blocks in down_read() before doing anything else; no memory is freed, over-read, or leaked, and no data is disclosed to the attacker.\nI:N - No memory corruption or data modification occurs — the only effect is a permanently held lock, which yields no write primitive.\nA:H - An unkillable D-state kworker holds sess->rpc_lock forever, blocking connection teardown and — via ksmbd_sessions_deregister() holding the global sessions_table_lock — all sessions server-wide; destroy_workqueue() also hangs, so ksmbd cannot be restarted or unloaded and recovery requires a reboot."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:07:42.312Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12.53","versionEndExcluding":"6.12.55"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17.3","versionEndExcluding":"6.17.5"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}