CVE-2024-43828: Loop with Unreachable Exit Condition

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

ext4: fix infinite loop when replaying fast_commit

When doing fast_commit replay an infinite loop may occur due to an uninitialized extent_status struct. ext4_ext_determine_insert_hole() does not detect the replay and calls ext4_es_find_extent_range(), which will return immediately without initializing the 'es' variable.

Because 'es' contains garbage, an integer overflow may happen causing an infinite loop in this function, easily reproducible using fstest generic/039.

This commit fixes this issue by unconditionally initializing the structure in function ext4_es_find_extent_range().

Thanks to Zhang Yi, for figuring out the real problem!