netdev - About ip6_dst

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <3e01083c-ba34-e515-bb3d-d85a98f90e61@gmail.com>
Date:   Sat, 27 Apr 2019 16:56:20 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     David Ahern <dsahern@...il.com>,
        Networking <netdev@...r.kernel.org>
Subject: About ip6_dst_destroy()

David

I am staring at ip6_dst_destroy() and the last part makes really no sense to me.

How rcu_read_lock()/rcu_read_unnlock() can help in a writer side ???

Changlog of a68886a691804d3f6d479ebf6825480fbafb6a00 ("net/ipv6: Make from in rt6_info rcu protected")
does not make sense either.

<quote>
    There is a race window when a FIB entry is deleted and the 'from' on the
    pcpu route is dropped and the pcpu route hits a cookie check. Handle
    this race using rcu on from.
</quote>