ksmbd: Fix race condition in RPC handle list access
The 'sess->rpc_handle_list' XArray manages RPC handles within a ksmbd
session. Access to this list is intended to be protected by
'sess->rpc_lock' (an rw_semaphore). However, the locking implementation was
flawed, leading to potential race conditions.
In ksmbd_session_rpc_open(), the code incorrectly acquired only a read lock
before calling xa_store() and xa_erase(). Since these operations modify
the XArray structure, a write lock is required to ensure exclusive access
and prevent data corruption from concurrent modifications.
Furthermore, ksmbd_session_rpc_method() accessed the list using xa_load()
without holding any lock at all. This could lead to reading inconsistent
data or a potential use-after-free if an entry is concurrently removed and
the pointer is dereferenced.
Fix these issues by:
1. Using down_write() and up_write() in ksmbd_session_rpc_open()
to ensure exclusive access during XArray modification, and ensuring
the lock is correctly released on error paths.
2. Adding down_read() and up_read() in ksmbd_session_rpc_method()
to safely protect the lookup.
| Source | ID | Title |
|---|---|---|
Debian DLA |
DLA-4476-1 | linux-6.1 security update |
Debian DSA |
DSA-6127-1 | linux security update |
Ubuntu USN |
USN-8029-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-8030-1 | Linux kernel (GCP) vulnerabilities |
Ubuntu USN |
USN-8029-2 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-8048-1 | Linux kernel (OEM) vulnerabilities |
Ubuntu USN |
USN-8029-3 | Linux kernel (Azure) vulnerabilities |
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
Fri, 06 Feb 2026 16:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Mon, 01 Dec 2025 06:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
Wed, 29 Oct 2025 11:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux
Linux linux Kernel |
|
| Vendors & Products |
Linux
Linux linux Kernel |
Wed, 29 Oct 2025 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Tue, 28 Oct 2025 12:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ksmbd: Fix race condition in RPC handle list access The 'sess->rpc_handle_list' XArray manages RPC handles within a ksmbd session. Access to this list is intended to be protected by 'sess->rpc_lock' (an rw_semaphore). However, the locking implementation was flawed, leading to potential race conditions. In ksmbd_session_rpc_open(), the code incorrectly acquired only a read lock before calling xa_store() and xa_erase(). Since these operations modify the XArray structure, a write lock is required to ensure exclusive access and prevent data corruption from concurrent modifications. Furthermore, ksmbd_session_rpc_method() accessed the list using xa_load() without holding any lock at all. This could lead to reading inconsistent data or a potential use-after-free if an entry is concurrently removed and the pointer is dereferenced. Fix these issues by: 1. Using down_write() and up_write() in ksmbd_session_rpc_open() to ensure exclusive access during XArray modification, and ensuring the lock is correctly released on error paths. 2. Adding down_read() and up_read() in ksmbd_session_rpc_method() to safely protect the lookup. | |
| Title | ksmbd: Fix race condition in RPC handle list access | |
| References |
|
Projects
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-02-06T16:31:25.885Z
Reserved: 2025-04-16T07:20:57.153Z
Link: CVE-2025-40039
No data.
Status : Awaiting Analysis
Published: 2025-10-28T12:15:37.847
Modified: 2026-02-06T17:16:17.070
Link: CVE-2025-40039
OpenCVE Enrichment
Updated: 2025-10-29T10:58:14Z
No weakness.
Debian DLA
Debian DSA
Ubuntu USN