Race Condition in Linux Kernel SMB Client During Rename Operations

CVE-2025-39825

What is CVE-2025-39825?

A race condition vulnerability has been identified in the SMB client of the Linux kernel during rename operations. This issue arises when a rename request is processed by the server, which simultaneously involves closing any deferred closes and waiting for outstanding I/O operations to complete. As a result, there is an increased window for potential concurrent opens on the target file, which can lead to unintended consequences. To mitigate this issue, the solution involves unhashing the dentry beforehand, which effectively prevents any concurrent opens of the file during the rename process.

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