Describe CVE-2021-47087.
What is CVE-2021-47087?
In the Linux kernel, the following vulnerability has been resolved:

tee: optee: Fix incorrect page free bug

Pointer to the allocated pages (struct page *page) has already
progressed towards the end of allocation. It is incorrect to perform
__free_pages(page, order) using this pointer as we would free any
arbitrary pages. Fix this by stop modifying the page pointer..