net: annotate sk->sk_err write from do_recvmmsg()

stable inclusion
from stable-v4.19.284
commit 640bce625ccf667a1a80262175a81108889ac41d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7J5UF


CVE: NA

--------------------------------

[ Upstream commit e05a5f51 ]

do_recvmmsg() can write to sk->sk_err from multiple threads.

As said before, many other points reading or writing sk_err
need annotations.

Fixes: 34b88a68 ("net: Fix use after free in the recvmmsg exit path")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Reviewed-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>