CVE-2025-39689

In the Linux kernel, the following vulnerability has been resolved:

ftrace: Also allocate and copy hash for reading of filter files

Currently the reader of set_ftrace_filter and set_ftrace_notrace just adds

the pointer to the global tracer hash to its iterator. Unlike the writer

that allocates a copy of the hash, the reader keeps the pointer to the

filter hashes. This is problematic because this pointer is static across

function calls that release the locks that can update the global tracer

hashes. This can cause UAF and similar bugs.

Allocate and copy the hash for reading the filter files like it is done

for the writers. This not only fixes UAF bugs, but also makes the code a

bit simpler as it doesn't have to differentiate when to free the

iterator's hash between writers and readers.