linux-ext4 - Re: [PATCH] ext4: Fix ext4_empty_dir() for directories with holes

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Message-ID: <20191127194415.GA22921@mit.edu>
Date:   Wed, 27 Nov 2019 14:44:15 -0500
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Jan Kara <jack@...e.cz>
Cc:     linux-ext4@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] ext4: Fix ext4_empty_dir() for directories with holes

On Wed, Nov 27, 2019 at 02:12:58PM +0100, Jan Kara wrote:
> Function ext4_empty_dir() doesn't correctly handle directories with
> holes and crashes on bh->b_data dereference when bh is NULL....

Hi Jan,

Thanks for the patch.

However, it looks like we're still vulnerable to the first block of
the directory being NULL?

> @@ -2833,19 +2833,25 @@ bool ext4_empty_dir(struct inode *inode)
>  		return true;
>  
>  	de = (struct ext4_dir_entry_2 *) bh->b_data;
                                         ^^^^^^^^^^^

						- Ted