ext4: fix check for block being out of directory size

commit 61a1d87a324ad5e3ed27c6699dfc93218fcf3201 upstream.

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: 65f8ea4cd57d ("ext4: check if directory block is within i_size")
CVE: CVE-2022-1184
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Link: https://lore.kernel.org/r/20220822114832.1482-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 7d3ec39121f728a30edaa1c12397ec8da1759609..86ee0e0eef67183bfbc34965c1092271a8c4ffaa 100644 (file)
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -126,7 +126,7 @@ 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);