x86/mm, kexec, ima: Use memblock_free_late() from ima_free_kexec_buffer()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: x86/mm, kexec, ima: Use memblock_free_late() from ima_free_kexec_buffer() The code calling ima_free_kexec_buffer() runs long after the memblock allocator has already been torn down, potentially resulting in a use after free in memblock_isolate_range(). With KASAN or KFENCE, this use after free will result in a BUG from the idle task, and a subsequent kernel panic. Switch ima_free_kexec_buffer() over to memblock_free_late() to avoid that bug.

References

• https://git.kernel.org/stable/c/eef16bfdb212da60f5144689f2967fb25b051a2b
• https://git.kernel.org/stable/c/d2dfbc0e3b7a04c2d941421a958dc31c897fb204
• https://git.kernel.org/stable/c/34cf99c250d5cd2530b93a57b0de31d3aaf8685b