lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date:   Mon,  4 Jul 2022 16:27:20 +0200
From:   Lukas Czerner <>
Subject: [PATCH 1/2] ext4: check if directory block is within i_size

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

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().

Signed-off-by: Lukas Czerner <>
Addresses Red-Hat-Bugzilla: #2070205
 fs/ext4/namei.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index db4ba99d1ceb..cf460aa4f81d 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -110,6 +110,13 @@ 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);
+	}
 	if (ext4_simulate_fail(inode->i_sb, EXT4_SIM_DIRBLOCK_EIO))
 		bh = ERR_PTR(-EIO);

Powered by blists - more mailing lists