CVE-2025-40039
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk22th percentile - higher than 22% of all known CVEs
Summary
In the Linux kernel, the ksmbd SMB server has a race condition in RPC handle list access. ksmbd_session_rpc_open() incorrectly used a read lock instead of write lock, and ksmbd_session_rpc_method() ran without any lock.
Risk Assessment
May lead to data corruption, inconsistent session state, or potential use-after-free, threatening SMB server stability and security.
Recommendation
Apply the Linux kernel patch that fixes locking in ksmbd: use write lock in ksmbd_session_rpc_open() and add read lock in ksmbd_session_rpc_method().
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In the Linux kernel XFS filesystem, during directory tree repair, a self-referential directory may be detected. In such a case, the repair code attempts to lock the same inode twice (double iolock/ilock), leading to a deadlock. The fix detects this corner case and handles it appropriately.
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Original NVD description (English source)
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.

