linux-kernel - Re: [PATCH 09/10][next] scsi: aacraid: Replace one-element array with flexible-array member in struct sgmap64

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Message-ID: <202306281344.FA95C5E@keescook>
Date:   Wed, 28 Jun 2023 13:46:34 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc:     aacraid@...rosemi.com, "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH 09/10][next] scsi: aacraid: Replace one-element array
 with flexible-array member in struct sgmap64

On Wed, Jun 28, 2023 at 11:57:30AM -0600, Gustavo A. R. Silva wrote:
> Replace one-element array with flexible-array member in struct
> sgmap64 and refactor the rest of the code, accordingly.
> 
> Issue found with the help of Coccinelle and audited and fixed,
> manually.

Like with the sgmap patch, I see (expected) binary differences in
aac_write_block64() and aac_read_block64() due to the simplified
calculations. I don't see anything unaccounted for, so:

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

> Link: https://github.com/KSPP/linux/issues/79
> Link: https://github.com/ClangBuiltLinux/linux/issues/1851
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
> ---
>  drivers/scsi/aacraid/aachba.c  | 9 +++------
>  drivers/scsi/aacraid/aacraid.h | 2 +-
>  2 files changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/scsi/aacraid/aachba.c b/drivers/scsi/aacraid/aachba.c
> index b2849e5cc104..90df697e7c5f 100644
> --- a/drivers/scsi/aacraid/aachba.c
> +++ b/drivers/scsi/aacraid/aachba.c
> @@ -1301,8 +1301,7 @@ static int aac_read_block64(struct fib * fib, struct scsi_cmnd * cmd, u64 lba, u
>  	if (ret < 0)
>  		return ret;
>  	fibsize = sizeof(struct aac_read64) +
> -		((le32_to_cpu(readcmd->sg.count) - 1) *
> -		 sizeof (struct sgentry64));
> +		  le32_to_cpu(readcmd->sg.count) * sizeof(struct sgentry64);
>  	BUG_ON (fibsize > (fib->dev->max_fib_size -
>  				sizeof(struct aac_fibhdr)));
>  	/*
> @@ -1433,8 +1432,7 @@ static int aac_write_block64(struct fib * fib, struct scsi_cmnd * cmd, u64 lba,
>  	if (ret < 0)
>  		return ret;
>  	fibsize = sizeof(struct aac_write64) +
> -		((le32_to_cpu(writecmd->sg.count) - 1) *
> -		 sizeof (struct sgentry64));
> +		  le32_to_cpu(writecmd->sg.count) * sizeof(struct sgentry64);
>  	BUG_ON (fibsize > (fib->dev->max_fib_size -
>  				sizeof(struct aac_fibhdr)));
>  	/*
> @@ -2271,8 +2269,7 @@ int aac_get_adapter_info(struct aac_dev* dev)
>  			dev->scsi_host_ptr->sg_tablesize =
>  				(dev->max_fib_size -
>  				sizeof(struct aac_fibhdr) -
> -				sizeof(struct aac_write64) +
> -				sizeof(struct sgentry64)) /
> +				sizeof(struct aac_write64)) /
>  					sizeof(struct sgentry64);
>  		} else {
>  			dev->a_ops.adapter_read = aac_read_block;
> diff --git a/drivers/scsi/aacraid/aacraid.h b/drivers/scsi/aacraid/aacraid.h
> index 3fbc22ae72b6..fb3d93e4a99e 100644
> --- a/drivers/scsi/aacraid/aacraid.h
> +++ b/drivers/scsi/aacraid/aacraid.h
> @@ -517,7 +517,7 @@ struct user_sgmap {
>  
>  struct sgmap64 {
>  	__le32		count;
> -	struct sgentry64 sg[1];
> +	struct sgentry64 sg[];
>  };
>  
>  struct user_sgmap64 {
> -- 
> 2.34.1
> 

-- 
Kees Cook