Uninitialized Pointer Dereference in Linux Kernel Affecting pNFS Functionality

CVE-2025-38691

What is CVE-2025-38691?

A vulnerability in the Linux kernel's pNFS implementation can allow an uninitialized pointer dereference during the encoding of extents. Specifically, as the 'ext_tree_prepare_commit()' function attempts to reallocate memory to encode extents, it does so without initializing the 'layoutupdate_pages' page array, leading to potential access violations. This flaw may escalate when dealing with larger files, resulting in layout commits exceeding the maximum RPC size accepted by the server. The risks are particularly pronounced when many extents are involved, as the reallocation may continuously fall short, exacerbating the issue.

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