net: Fix unwanted sign extension in netdev_stats_to_stats64()

stable inclusion
from stable-v4.19.296
commit b17d81b94d24834d0ee038c6e216752f43b67cc9
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I95ATV
CVE: CVE-2023-52578

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b17d81b94d24834d0ee038c6e216752f43b67cc9



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[ Upstream commit 9b55d3f0 ]

When converting net_device_stats to rtnl_link_stats64 sign extension
is triggered on ILP32 machines as 6c1c5097 changed the previous
"ulong -> u64" conversion to "long -> u64" by accessing the
net_device_stats fields through a (signed) atomic_long_t.

This causes for example the received bytes counter to jump to 16EiB after
having received 2^31 bytes. Casting the atomic value to "unsigned long"
beforehand converting it into u64 avoids this.

Fixes: 6c1c5097 ("net: add atomic_long_t to net_device_stats fields")
Signed-off-by: Felix Riemann <felix.riemann@sma.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>