icmp: Fix a data-race around sysctl_icmp_ratelimit.

stable inclusion
from stable-4.19.253
commit 9b07e84b2bcf5e42302070d693e3464fdef9d844
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5I4FP


CVE: NA

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[ Upstream commit 2a4eb714 ]

While reading sysctl_icmp_ratelimit, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>