ext4: fix check for block being out of directory size

mainline inclusion
from mainline-v6.1-rc1
commit 61a1d87a
category: bugfix
bugzilla: 186639, https://gitee.com/openeuler/kernel/issues/I58WSQ
CVE: CVE-2022-1184

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=61a1d87a324ad5e3ed27c6699dfc93218fcf3201

--------------------------------

The check in __ext4_read_dirblock() for block being outside of directory
size was wrong because it compared block number against directory size
in bytes. Fix it.

Fixes: 65f8ea4c ("ext4: check if directory block is within i_size")
CVE: CVE-2022-1184
CC: stable@vger.kernel.org
Signed-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NLukas Czerner <lczerner@redhat.com>
Link: https://lore.kernel.org/r/20220822114832.1482-1-jack@suse.czSigned-off-by: NTheodore Ts'o <tytso@mit.edu>
Signed-off-by: NBaokun Li <libaokun1@huawei.com>
Reviewed-by: NZhang Yi <yi.zhang@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

fs/ext4/namei.c

@@ -125,7 +125,7 @@ static struct buffer_head *__ext4_read_dirblock(struct inode *inode,
 	struct ext4_dir_entry *dirent;
 	int is_dx_block = 0;
 
-	if (block >= inode->i_size) {
+	if (block >= inode->i_size >> inode->i_blkbits) {
 		ext4_error_inode(inode, func, line, block,
 		       "Attempting to read directory block (%u) that is past i_size (%llu)",
 		       block, inode->i_size);