Re: [PATCH v1 2/2] s390x: Fix SCLP return code when buffer too small

[Thomas Huth <thuth@redhat.com>]

On 26/09/2019 13.33, Claudio Imbrenda wrote:
> Return the correct error code when the SCCB buffer is too small to
> contain all of the output, for the Read SCP Information and
> Read CPU Information commands.
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> Reviewed-by: Jason J. Herne <jjherne@linux.ibm.com>
> ---
>  hw/s390x/sclp.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
> index 76feac8..8f7fe1c 100644
> --- a/hw/s390x/sclp.c
> +++ b/hw/s390x/sclp.c
> @@ -68,6 +68,11 @@ static void read_SCP_info(SCLPDevice *sclp, SCCB *sccb)
>  
>      read_info->ibc_val = cpu_to_be32(s390_get_ibc_val());
>  
> +    if (sccb->h.length < (sizeof(ReadInfo) + cpu_count * sizeof(CPUEntry))) {

Don't you need a cpu16_to_cpu() around sccb->h.length?

> +        sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
> +        return;
> +    }
> +
>      /* Configuration Characteristic (Extension) */
>      s390_get_feat_block(S390_FEAT_TYPE_SCLP_CONF_CHAR,
>                           read_info->conf_char);
> @@ -118,6 +123,11 @@ static void sclp_read_cpu_info(SCLPDevice *sclp, SCCB *sccb)
>      cpu_info->offset_configured = cpu_to_be16(offsetof(ReadCpuInfo, entries));
>      cpu_info->nr_standby = cpu_to_be16(0);
>  
> +    if (sccb->h.length < (sizeof(ReadCpuInfo) + cpu_count * sizeof(CPUEntry))) {

dito?

> +        sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
> +        return;
> +    }
> +
>      /* The standby offset is 16-byte for each CPU */
>      cpu_info->offset_standby = cpu_to_be16(cpu_info->offset_configured
>          + cpu_info->nr_configured*sizeof(CPUEntry));
> 

 Thomas