ocfs2: reject dinodes whose i_rdev disagrees with the file type

id1.dev1.i_rdev is the device-number arm of the ocfs2_dinode id1 union. 
It is only meaningful for character and block device inodes.  For any
other user-visible file type the on-disk value must be zero.

ocfs2_populate_inode() currently copies id1.dev1.i_rdev into inode->i_rdev
before the S_IFMT switch decides whether the inode is a special file.  A
non-device inode with a non-zero i_rdev can therefore publish stale or
attacker-controlled device state into the in-core inode.

System inodes legitimately use other arms of the same union, so keep the
cross-check restricted to non-system inodes.  Factor that predicate into a
helper and use it in both the normal validator and online filecheck path;
filecheck reports the malformed dinode through
OCFS2_FILECHECK_ERR_INVALIDINO instead of ocfs2_error().

Link: https://lore.kernel.org/20260519110404.1803902-3-michael.bommarito@gmail.com
Fixes: b657c95c1108 ("ocfs2: Wrap inode block reads in a dedicated function.")
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Assisted-by: Claude:claude-opus-4-7
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Heming Zhao <heming.zhao@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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