Usercopy Vulnerability in Linux Kernel CIFS Component

CVE-2025-38523

What is CVE-2025-38523?

A usercopy vulnerability exists in the CIFS component of the Linux kernel, where improper handling of data in the smbd_response struct can lead to kernel memory exposure. This issue arises when the packet field of the smbd_response slab is not correctly marked as permissible for usercopy operations. When CONFIG_HARDENED_USERCOPY is enabled, attempts to copy data can trigger kernel crashes, presenting a serious stability and security risk. Fixing this vulnerability involves modifying parameters during slab creation to ensure proper permissions for the usercopy function in the affected areas.

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