linux-kernel - Re: [PATCH] sd: fix uninitialized variable access in error handling

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Date:   Mon, 24 Oct 2016 16:37:07 +0200
From:   Hannes Reinecke <hare@...e.de>
To:     Arnd Bergmann <arnd@...db.de>,
        "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     Shaun Tancheff <shaun.tancheff@...gate.com>,
        Jens Axboe <axboe@...com>,
        Damien Le Moal <damien.lemoal@...t.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sd: fix uninitialized variable access in error handling

On 10/21/2016 05:32 PM, Arnd Bergmann wrote:
> If sd_zbc_report_zones fails, the check for 'zone_blocks == 0'
> later in the function accesses uninitialized data:
>
> drivers/scsi/sd_zbc.c: In function ‘sd_zbc_read_zones’:
> drivers/scsi/sd_zbc.c:520:7: error: ‘zone_blocks’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> This sets it to zero, which has the desired effect of leaving
> the sd_zbc_read_zones successfully with sdkp->zone_blocks = 0.
>
> Fixes: 89d947561077 ("sd: Implement support for ZBC devices")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/scsi/sd_zbc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
> index 16d3fa62d8ac..d5b3bd915d9e 100644
> --- a/drivers/scsi/sd_zbc.c
> +++ b/drivers/scsi/sd_zbc.c
> @@ -455,8 +455,10 @@ static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)
>
>  	/* Do a report zone to get the same field */
>  	ret = sd_zbc_report_zones(sdkp, buf, SD_ZBC_BUF_SIZE, 0);
> -	if (ret)
> +	if (ret) {
> +		zone_blocks = 0;
>  		goto out;
> +	}
>
>  	same = buf[4] & 0x0f;
>  	if (same > 0) {
>
Reviewed-by: Hannes Reinecke <hare@...e.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@...e.de			               +49 911 74053 688
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