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

[Damien Le Moal]

On 10/22/16 00:32, 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 âsd_zbc_read_zonesâ:
> drivers/scsi/sd_zbc.c:520:7: error: âzone_blocksâ 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@xxxxxxxx>
> ---
>  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: Damien Le Moal <damien.lemoal@xxxxxxx>

-- 
Damien Le Moal, Ph.D.
Sr. Manager, System Software Research Group,
Western Digital Corporation
Damien.LeMoal@xxxxxxx
(+81) 0466-98-3593 (ext. 513593)
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