udf: reject extents past EOF when extending a file

udf_extend_file() warns when inode_bmap() reports the last extent as
longer than the block the file is being extended in:

	WARN_ON_ONCE(within_last_ext &&
		     elen > ((loff_t)offset + 1) << inode->i_blkbits);

A corrupted image can trigger this, as syzbot reports for
udf_setsize():

  WARNING: CPU: 1 PID: 6098 at fs/udf/inode.c:684 udf_extend_file fs/udf/inode.c:683 [inline]
  WARNING: CPU: 1 PID: 6098 at fs/udf/inode.c:684 udf_setsize+0xd5a/0x1010 fs/udf/inode.c:1300

The extent really is invalid, so there is nothing to warn about: report
it with udf_err() and fail the truncate with -EFSCORRUPTED instead of
tainting the kernel.

Reported-by: syzbot+db6df8c0f578bc11e50e@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=db6df8c0f578bc11e50e
Fixes: 16d055656814 ("udf: Discard preallocation before extending file with a hole")
Signed-off-by: xujiahao <xujiahao@cmss.chinamobile.com>
Link: https://patch.msgid.link/20261109013952.449019-1-xujiahao@cmss.chinamobile.com
Signed-off-by: Jan Kara <jack@suse.cz>