linux-ext4 - Re: [PATCH 1/2] ext4: Verify dir block before splitting it

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Message-ID: <20220518090956.ttowg7yweyqbshmp@quack3.lan>
Date:   Wed, 18 May 2022 11:09:56 +0200
From:   Jan Kara <jack@...e.cz>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH 1/2] ext4: Verify dir block before splitting it

On Tue 17-05-22 19:40:11, Theodore Ts'o wrote:
> On Thu, Apr 28, 2022 at 08:31:37PM +0200, Jan Kara wrote:
> > Before splitting a directory block verify its directory entries are sane
> > so that the splitting code does not access memory it should not.
> 
> This commit fails to build due to an undefined variable.  It's fixed
> with this hunk in the next patch, which needs to be brought back into
> this commit:
> 
> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> index 5951e9bb348e..7286472e9558 100644
> --- a/fs/ext4/namei.c
> +++ b/fs/ext4/namei.c
> @@ -1278,7 +1278,7 @@ static int dx_make_map(struct inode *dir, struct buffer_head *bh,
>  			count++;
>  			cond_resched();
>  		}
> -		de = ext4_next_entry(de, blocksize);
> +		de = ext4_next_entry(de, dir->i_sb->s_blocksize);
>  	}
>  	return count;
>  }
> 
> I was thinking about folding in this change and apply the patch with
> that change --- and I may yet do that --- but it looks like there's a
> bigger problem with this patch series, which is that it's causing a
> crash when running ext4/052 due to what appears to be a smashed stack.
> More about that in the reply to patch 2/2 of this series....

Yup, I'll fix that. Thanks for catching this.

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR