CVE-2026-43076: ocfs2: validate inline data i_size during inode read

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

ocfs2: validate inline data isize during inode read

When reading an inode from disk, ocfs2validateinodeblock() performs various sanity checks but does not validate the size of inline data. If the filesystem is corrupted, an inode's isize can exceed the actual inline data capacity (idcount).

This causes ocfs2dirforeachblkid() to iterate beyond the inline data buffer, triggering a use-after-free when accessing directory entries from freed memory.

In the syzbot report: - isize was 1099511627576 bytes (~1TB) - Actual inline data capacity (idcount) is typically <256 bytes - A garbage reclen (54648) caused ctx->pos to jump out of bounds - This triggered a UAF in ocfs2checkdirentry()

Fix by adding a validation check in ocfs2validateinodeblock() to ensure inodes with inline data have isize <= idcount. This catches the corruption early during inode read and prevents all downstream code from operating on invalid data.