In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix recursive locking in RPC handle list access

Since commit 305853cce3794 ("ksmbd: Fix race condition in RPC handle list
access"), ksmbd_session_rpc_method() attempts to lock sess->rpc_lock.

This causes hung connections / tasks when a client attempts to open
a named pipe. Using Samba's rpcclient tool:

$ rpcclient //192.168.1.254 -U user%password
$ rpcclient $> srvinfo
<connection hung here>

Kernel side:
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:0 state:D stack:0 pid:5021 tgid:5021 ppid:2 flags:0x00200000
Workqueue: ksmbd-io handle_ksmbd_work
Call trace:
__schedule from schedule+0x3c/0x58
schedule from schedule_preempt_disabled+0xc/0x10
schedule_preempt_disabled from rwsem_down_read_slowpath+0x1b0/0x1d8
rwsem_down_read_slowpath from down_read+0x28/0x30
down_read from ksmbd_session_rpc_method+0x18/0x3c
ksmbd_session_rpc_method from ksmbd_rpc_open+0x34/0x68
ksmbd_rpc_open from ksmbd_session_rpc_open+0x194/0x228
ksmbd_session_rpc_open from create_smb2_pipe+0x8c/0x2c8
create_smb2_pipe from smb2_open+0x10c/0x27ac
smb2_open from handle_ksmbd_work+0x238/0x3dc
handle_ksmbd_work from process_scheduled_works+0x160/0x25c
process_scheduled_works from worker_thread+0x16c/0x1e8
worker_thread from kthread+0xa8/0xb8
kthread from ret_from_fork+0x14/0x38
Exception stack(0x8529ffb0 to 0x8529fff8)

The task deadlocks because the lock is already held:
ksmbd_session_rpc_open
down_write(&sess->rpc_lock)
ksmbd_rpc_open
ksmbd_session_rpc_method
down_read(&sess->rpc_lock) <-- deadlock

Adjust ksmbd_session_rpc_method() callers to take the lock when necessary.
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 30 Oct 2025 14:45:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Vendors & Products Linux
Linux linux Kernel

Thu, 30 Oct 2025 10:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix recursive locking in RPC handle list access Since commit 305853cce3794 ("ksmbd: Fix race condition in RPC handle list access"), ksmbd_session_rpc_method() attempts to lock sess->rpc_lock. This causes hung connections / tasks when a client attempts to open a named pipe. Using Samba's rpcclient tool: $ rpcclient //192.168.1.254 -U user%password $ rpcclient $> srvinfo <connection hung here> Kernel side: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/0:0 state:D stack:0 pid:5021 tgid:5021 ppid:2 flags:0x00200000 Workqueue: ksmbd-io handle_ksmbd_work Call trace: __schedule from schedule+0x3c/0x58 schedule from schedule_preempt_disabled+0xc/0x10 schedule_preempt_disabled from rwsem_down_read_slowpath+0x1b0/0x1d8 rwsem_down_read_slowpath from down_read+0x28/0x30 down_read from ksmbd_session_rpc_method+0x18/0x3c ksmbd_session_rpc_method from ksmbd_rpc_open+0x34/0x68 ksmbd_rpc_open from ksmbd_session_rpc_open+0x194/0x228 ksmbd_session_rpc_open from create_smb2_pipe+0x8c/0x2c8 create_smb2_pipe from smb2_open+0x10c/0x27ac smb2_open from handle_ksmbd_work+0x238/0x3dc handle_ksmbd_work from process_scheduled_works+0x160/0x25c process_scheduled_works from worker_thread+0x16c/0x1e8 worker_thread from kthread+0xa8/0xb8 kthread from ret_from_fork+0x14/0x38 Exception stack(0x8529ffb0 to 0x8529fff8) The task deadlocks because the lock is already held: ksmbd_session_rpc_open down_write(&sess->rpc_lock) ksmbd_rpc_open ksmbd_session_rpc_method down_read(&sess->rpc_lock) <-- deadlock Adjust ksmbd_session_rpc_method() callers to take the lock when necessary.
Title ksmbd: fix recursive locking in RPC handle list access
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-10-30T09:47:58.611Z

Reserved: 2025-04-16T07:20:57.162Z

Link: CVE-2025-40090

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2025-10-30T10:15:33.537

Modified: 2025-10-30T15:03:13.440

Link: CVE-2025-40090

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2025-10-30T14:37:18Z