netpoll: Fix race condition in netpoll_owner_active

mainline inclusion
from mainline-v6.10-rc1
commit c2e6a872bde9912f1a7579639c5ca3adf1003916
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IACR1O
CVE: CVE-2024-41005

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c2e6a872bde9912f1a7579639c5ca3adf1003916



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

KCSAN detected a race condition in netpoll:

	BUG: KCSAN: data-race in net_rx_action / netpoll_send_skb
	write (marked) to 0xffff8881164168b0 of 4 bytes by interrupt on cpu 10:
	net_rx_action (./include/linux/netpoll.h:90 net/core/dev.c:6712 net/core/dev.c:6822)
<snip>
	read to 0xffff8881164168b0 of 4 bytes by task 1 on cpu 2:
	netpoll_send_skb (net/core/netpoll.c:319 net/core/netpoll.c:345 net/core/netpoll.c:393)
	netpoll_send_udp (net/core/netpoll.c:?)
<snip>
	value changed: 0x0000000a -> 0xffffffff

This happens because netpoll_owner_active() needs to check if the
current CPU is the owner of the lock, touching napi->poll_owner
non atomically. The ->poll_owner field contains the current CPU holding
the lock.

Use an atomic read to check if the poll owner is the current CPU.

Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/r/20240429100437.3487432-1-leitao@debian.org


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

Conflicts:
	net/core/netpoll.c
[The conflict occurs because the commit 5251ef82("net: make sure
napi_list is safe for RCU traversal") is not merged]
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>