On 7/28/21 2:01 PM, Kees Cook wrote:
> On Wed, Jul 28, 2021 at 07:55:53AM +0200, Greg Kroah-Hartman wrote:
>>>  struct ethhdr {
>>> -   unsigned char   h_dest[ETH_ALEN];       /* destination eth addr */
>>> -   unsigned char   h_source[ETH_ALEN];     /* source ether addr    */
>>> +   union {
>>> +           struct {
>>> +                   unsigned char h_dest[ETH_ALEN];   /* destination eth 
>>> addr */
>>> +                   unsigned char h_source[ETH_ALEN]; /* source ether addr  
>>>   */
>>> +           };
>>> +           struct {
>>> +                   unsigned char h_dest[ETH_ALEN];   /* destination eth 
>>> addr */
>>> +                   unsigned char h_source[ETH_ALEN]; /* source ether addr  
>>>   */
>>> +           } addrs;
>>
>> A union of the same fields in the same structure in the same way?
>>
>> Ah, because struct_group() can not be used here?  Still feels odd to see
>> in a userspace-visible header.
> 
> Yeah, there is some inconsistency here. I will clean this up for v2.
> 
> Is there a place we can put kernel-specific macros for use in UAPI
> headers? (I need to figure out where things like __kernel_size_t get
> defined...)

How about using two memset() calls to clear h_dest[] and h_source[]
instead of modifying the uapi header?

Thanks,

Bart.


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