CVE-2025-21815

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

mm/compaction: fix UBSAN shift-out-of-bounds warning

syzkaller reported a UBSAN shift-out-of-bounds warning of (1UL << order) in isolate_freepages_block(). The bogus compound_order can be any value because it is union with flags. Add back the MAX_PAGE_ORDER check to fix the warning. More information : https://git.kernel.org/stable/c/10b7d3eb535098ccd4c82a182a33655d8a0e5c88