net: ping: do not abuse udp_poll()

commit 77d4b1d3 upstream.

Alexander reported various KASAN messages triggered in recent kernels

The problem is that ping sockets should not use udp_poll() in the first
place, and recent changes in UDP stack finally exposed this old bug.

Fixes: c319b4d7 ("net: ipv4: add IPPROTO_ICMP socket kind")
Fixes: 6d0bfe22

 ("net: ipv6: Add IPv6 support to the ping socket.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Sasha Levin <alexander.levin@verizon.com>
Cc: Solar Designer <solar@openwall.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Acked-By: Lorenzo Colitti <lorenzo@google.com>
Tested-By: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[wt: removed the parts related to ping6 as 6d0bfe22

 is not in 3.10]

Signed-off-by: Willy Tarreau <w@1wt.eu>