Linux Kernel CIFS Use-After-Free Vulnerability in DFS Cache Handling

A use-after-free vulnerability has been identified in the Linux kernel's CIFS (Common Internet File System) implementation, specifically within the DFS (Distributed File System) cache management. This vulnerability arises because DFS root sessions were being released while the DFS cache refresher was still active, leading to a use-after-free condition. The issue was detected by KASAN (Kernel Address Sanitizer), which reported a read of freed memory by a kernel worker thread processing DFS cache updates. The vulnerability has been addressed by synchronizing the lifetimes of DFS root sessions with DFS connection management, eliminating the need for mount group handling in the DFS cache.

Impact

Exploitation of this vulnerability could lead to memory corruption issues, allowing for potential arbitrary code execution or other undefined behavior in the kernel.