From d9dc377b05ac4ada7b67b8db0b809723af7e4547 Mon Sep 17 00:00:00 2001
From: Lukas Czerner <lczerner@redhat.com>
Date: Mon, 10 Oct 2022 09:37:43 +0000
Subject: [PATCH] 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
--------------------------------
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
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/20220704142721.157985-1-lczerner@redhat.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Conflicts:
fs/ext4/namei.c
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>
---
fs/ext4/namei.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index b2d4fb82e8f4..1a9eda144c7a 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -124,6 +124,13 @@ 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) {
+ ext4_error_inode(inode, func, line, block,
+ "Attempting to read directory block (%u) that is past i_size (%llu)",
+ block, inode->i_size);
+ return ERR_PTR(-EFSCORRUPTED);
+ }
+
bh = ext4_bread(NULL, inode, block, 0);
if (IS_ERR(bh)) {
__ext4_warning(inode->i_sb, func, line,
--
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