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.