Re: [Qemu-devel] [PATCHv3] qdev: Validate hex properties

[Andreas Färber]

Am 28.11.2013 09:39, schrieb Hannes Reinecke:
> strtoul(l) might overflow, in which case it'll return '-1' and set
> the appropriate error code. So update the calls to strtoul(l) when
> parsing hex properties to avoid silent overflows.
> 
> Signed-off-by: Hannes Reinecke <address@hidden>
> ---
>  hw/core/qdev-properties.c | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
> index dc8ae69..4891a01 100644
> --- a/hw/core/qdev-properties.c
> +++ b/hw/core/qdev-properties.c
> @@ -191,6 +191,7 @@ PropertyInfo qdev_prop_uint8 = {
>  
>  static int parse_hex8(DeviceState *dev, Property *prop, const char *str)
>  {
> +    unsigned long val;
>      uint8_t *ptr = qdev_get_prop_ptr(dev, prop);
>      char *end;
>  
> @@ -198,11 +199,18 @@ static int parse_hex8(DeviceState *dev, Property *prop, 
> const char *str)
>          return -EINVAL;
>      }
>  
> -    *ptr = strtoul(str, &end, 16);
> +    errno = 0;
> +    val = strtoul(str, &end, 16);
> +    if (errno) {
> +        return -errno;
> +    }
> +    if (val > 255) {
> +        return -ERANGE;
> +    }
>      if ((*end != '\0') || (end == str)) {
>          return -EINVAL;
>      }
> -
> +    *ptr = val;
>      return 0;
>  }
>  

This part looks okay to me.

> @@ -329,7 +337,11 @@ static int parse_hex32(DeviceState *dev, Property *prop, 
> const char *str)
>          return -EINVAL;
>      }
>  
> +    errno = 0;
>      *ptr = strtoul(str, &end, 16);
> +    if (errno) {
> +        return -errno;
> +    }

I can image that on a 64-bit system long can be larger than 32 bits, so
we'll need an equivalent val > UINT32_MAX check here, I guess?

>      if ((*end != '\0') || (end == str)) {
>          return -EINVAL;
>      }
> @@ -396,7 +408,11 @@ static int parse_hex64(DeviceState *dev, Property *prop, 
> const char *str)
>          return -EINVAL;
>      }
>  
> +    errno = 0;
>      *ptr = strtoull(str, &end, 16);
> +    if (errno) {
> +        return -errno;
> +    }
>      if ((*end != '\0') || (end == str)) {
>          return -EINVAL;
>      }

Eric, do we have any size guarantee for long long or do we also need a
symmetric if (... > UINT64_MAX) { return -ERANGE; } for the unlikely
128-bit case?

Andreas

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