net: fix possible store tearing in neigh_periodic_work()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: net: fix possible store tearing in neigh_periodic_work() While looking at a related syzbot report involving neigh_periodic_work(), I found that I forgot to add an annotation when deleting an RCU protected item from a list. Readers use rcu_deference(*np), we need to use either rcu_assign_pointer() or WRITE_ONCE() on writer side to prevent store tearing. I use rcu_assign_pointer() to have lockdep support, this was the choice made in neigh_flush_dev().

References

• https://git.kernel.org/stable/c/95eabb075a5902f4c0834ab1fb12dc35730c05af
• https://git.kernel.org/stable/c/2ea52a2fb8e87067e26bbab4efb8872639240eb0
• https://git.kernel.org/stable/c/147d89ee41434b97043c2dcb17a97dc151859baa
• https://git.kernel.org/stable/c/f82aac8162871e87027692b36af335a2375d4580
• https://git.kernel.org/stable/c/a75152d233370362eebedb2643592e7c883cc9fc
• https://git.kernel.org/stable/c/25563b581ba3a1f263a00e8c9a97f5e7363be6fd