linux-kernel - Re: [PATCH] md/raid5: Convert stripe_head's "dev" to flexible array member

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZGWpLClY7vz+xl5A@infradead.org>
Date:   Wed, 17 May 2023 21:27:24 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Song Liu <song@...nel.org>, linux-raid@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] md/raid5: Convert stripe_head's "dev" to flexible array
 member

On Wed, May 17, 2023 at 04:33:14PM -0700, Kees Cook wrote:
>  	sc = kmem_cache_create(conf->cache_name[conf->active_name],
> -			       sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
> +			       struct_size((struct stripe_head *)0, dev, devs),
>  			       0, 0, NULL);
>  	if (!sc)
>  		return 1;
> @@ -2559,7 +2559,7 @@ static int resize_stripes(struct r5conf *conf, int newsize)
>  
>  	/* Step 1 */
>  	sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
> -			       sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
> +			       struct_size((struct stripe_head *)0, dev, newsize),

The constant you're casting here should be NULL, not 0.
Also given that this expression is duplicated, I'd suggest a little
helper for it…

> -	} dev[1]; /* allocated with extra space depending of RAID geometry */
> +	} dev[]; /* allocated with extra space depending of RAID geometry */

And this isn't extra space over the single entry anymore, so I'd
change this to:

	/* allocated depending of RAID geometry */