Re: [Xen-devel] [PATCH v6 3/6] xen: Introduce a helper to read a u32 property in device tree.

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 12 August 2013 16:19, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> On 08/09/2013 03:20 AM, Chen Baozi wrote:
>> Signed-off-by: Chen Baozi <baozich@xxxxxxxxx>
> Acked-by: Julien Grall <julien.grall@xxxxxxxxxx>
>> ---
>>  xen/common/device_tree.c      | 15 +++++++++++++++
>>  xen/include/xen/device_tree.h | 11 +++++++++++
>>  2 files changed, 26 insertions(+)
>>
>> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
>> index 84d704d..a4701eb 100644
>> --- a/xen/common/device_tree.c
>> +++ b/xen/common/device_tree.c
>> @@ -574,6 +574,21 @@ const void *dt_get_property(const struct dt_device_node 
>> *np,
>>      return pp ? pp->value : NULL;
>>  }
>>
>> +bool_t dt_property_read_u32(const struct dt_device_node *np,
>> +                         const char *name, u32 *out_value)
>> +{
>> +    u32 len;
>> +    const __be32 *val;
>> +
>> +    val = dt_get_property(np, name, &len);
>> +    if ( !val || len > sizeof(*out_value) )
>> +        return 0;

Hum .. I have just noticed that the check is wrong.
Len must be greater or equal to sizeof (*out_value). Otherwise you can
read random bytes.


>> +
>> +    *out_value = be32_to_cpup(val);
>> +
>> +    return 1;
>> +}
>> +
>>  bool_t dt_device_is_compatible(const struct dt_device_node *device,
>>                                 const char *compat)
>>  {
>> diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
>> index 5a2a5c6..faf727f 100644
>> --- a/xen/include/xen/device_tree.h
>> +++ b/xen/include/xen/device_tree.h
>> @@ -300,6 +300,17 @@ const void *dt_get_property(const struct dt_device_node 
>> *np,
>>                              const char *name, u32 *lenp);
>>
>>  /**
>> + * dt_property_read_u32 - Helper to read a u32 property.
>> + * @np: node to get the value
>> + * @name: name of the property
>> + * @out_value: pointer to return value
>> + *
>> + * Return true if get the desired value.
>> + */
>> +bool_t dt_property_read_u32(const struct dt_device_node *np,
>> +                            const char *name, u32 *out_value);
>> +
>> +/**
>>   * Checks if the given "compat" string matches one of the strings in
>>   * the device's "compatible" property
>>   */
>>
>
>
> --
> Julien Grall



-- 
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel