ext4: check if directory block is within i_size

mainline inclusion
from mainline-v6.0-rc1
commit 65f8ea4cd57dbd46ea13b41dc8bac03176b04233
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I58WSQ
CVE: CVE-2022-1184

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Currently ext4 directory handling code implicitly assumes that the
directory blocks are always within the i_size. In fact ext4_append()
will attempt to allocate next directory block based solely on i_size and
the i_size is then appropriately increased after a successful
allocation.

However, for this to work it requires i_size to be correct. If, for any
reason, the directory inode i_size is corrupted in a way that the
directory tree refers to a valid directory block past i_size, we could
end up corrupting parts of the directory tree structure by overwriting
already used directory blocks when modifying the directory.

Fix it by catching the corruption early in __ext4_read_dirblock().

Addresses Red-Hat-Bugzilla: #2070205
CVE: CVE-2022-1184...