netdev - Re: [PATCH net] rxrpc: use rcu protection while reading sk->sk_user

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:   Thu, 17 Oct 2019 00:24:36 +0100
From:   David Howells <dhowells@...hat.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     dhowells@...hat.com, "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: Re: [PATCH net] rxrpc: use rcu protection while reading sk->sk_user_data

Eric Dumazet <edumazet@...gle.com> wrote:

> We need to extend the rcu_read_lock() section in rxrpc_error_report()
> and use rcu_dereference_sk_user_data() instead of plain access
> to sk->sk_user_data to make sure all rules are respected.

Should I take it that the caller won't be guaranteed to be holding the RCU
read lock?

Looking at __udp4_lib_err(), that calls __udp4_lib_err_encap(), which calls
__udp4_lib_err_encap_no_sk(), which should throw a warning if the RCU read
lock is not held.

Similarly, icmp_socket_deliver() and icmpv6_notify() should also throw a
warning before calling ->err_handler().

Does that mean something further up the CPU stack is going to be holding the
RCU read lock?

David