ocfs2: fix out-of-bounds write in ocfs2_write_end_inline

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

ocfs2: fix out-of-bounds write in ocfs2_write_end_inline

KASAN reports a use-after-free write of 4086 bytes in

ocfs2_write_end_inline, called from ocfs2_write_end_nolock during a

copy_file_range splice fallback on a corrupted ocfs2 filesystem mounted on

a loop device. The actual bug is an out-of-bounds write past the inode

block buffer, not a true use-after-free. The write overflows into an

adjacent freed page, which KASAN reports as UAF.

The root cause is that ocfs2_try_to_write_inline_data trusts the on-disk

id_count field to determine whether a write fits in inline data. On a

corrupted filesystem, id_count can exceed the physical maximum inline data

capacity, causing writes to overflow the inode block buffer.

Call trace (crash path):

vfs_copy_file_range (fs/read_write.c:1634)

do_splice_direct

splice_direct_to_actor

iter_file_splice_write

ocfs2_file_write_iter

generic_perform_write

ocfs2_write_end

ocfs2_write_end_nolock (fs/ocfs2/aops.c:1949)

ocfs2_write_end_inline (fs/ocfs2/aops.c:1915)

memcpy_from_folio <-- KASAN: write OOB

So add id_count upper bound check in ocfs2_validate_inode_block() to

alongside the existing i_size check to fix it.