net: Fix incorrect address comparison when searching for a bind2 bucket

The v6_rcv_saddr and rcv_saddr are inside a union in the
'struct inet_bind2_bucket'.  When searching a bucket by following the
bhash2 hashtable chain, eg. inet_bind2_bucket_match, it is only using
the sk->sk_family and there is no way to check if the inet_bind2_bucket
has a v6 or v4 address in the union.  This leads to an uninit-value
KMSAN report in [0] and also potentially incorrect matches.

This patch fixes it by adding a family member to the inet_bind2_bucket
and then tests 'sk->sk_family != tb->family' before matching
the sk's address to the tb's address.

Cc: Joanne Koong <joannelkoong@gmail.com>
Fixes: 28044fc1 ("net: Add a bhash2 table hashed by port and address")
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Tested-by: Alexander Potapenko <glider@google.com>
Link: https://lore.kernel.org/r/20220927002544.3381205-1-kafai@fb.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>