From: Lukas Czerner lczerner@redhat.com
commit 65f8ea4cd57dbd46ea13b41dc8bac03176b04233 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/namei.c | 7 +++++++ 1 file changed, 7 insertions(+)
--- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -109,6 +109,13 @@ static struct buffer_head *__ext4_read_d 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); + } + if (ext4_simulate_fail(inode->i_sb, EXT4_SIM_DIRBLOCK_EIO)) bh = ERR_PTR(-EIO); else