Re: [iptables PATCH] ruleparse: arp: Fix for all-zero mask on Big Endian

[Florian Westphal <fw@strlen.de>]

Phil Sutter <phil@nwl.cc> wrote:
> With 16bit mask values, the first two bytes of bitwise.mask in struct
> nft_xt_ctx_reg are significant. Reading the first 32bit-sized field
> works only on Little Endian, on Big Endian the mask appears in the upper
> two bytes which are discarded when assigning to a 16bit variable.

nft-ruleparse-arp.c: In function 'nft_arp_parse_payload':
nft-ruleparse-arp.c:93:77: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
   93 |                         fw->arp.arhrd_mask = ((uint16_t *)reg->bitwise.mask)[0];
      |                                                                             ^
nft-ruleparse-arp.c:102:77: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
  102 |                         fw->arp.arpro_mask = ((uint16_t *)reg->bitwise.mask)[0];
      |                                                                             ^
nft-ruleparse-arp.c:111:77: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
  111 |                         fw->arp.arpop_mask = ((uint16_t *)reg->bitwise.mask)[0];
      |                                                                             ^