Re: [PATCH] ext4: Fix check for block being out of directory size

Lukas Czerner
2022-08-23T12:56:24Z

On Mon, Aug 22, 2022 at 01:48:32PM +0200, Jan Kara wrote:
> 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.

Good catch, thanks!

Reviewed-by: Lukas Czerner <lczerner@redhat.com>

>
> 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>
> ---
> fs/ext4/namei.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> index 3a31b662f661..bc2e0612ec32 100644
> --- 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);
> --
> 2.35.3
>