netdev - Re: [PATCH net v2 1/2] wireguard: device: don't call free_netdev() in priv

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]

Message-ID: <CAHmME9rH7iBZN3tMuWuRU_n_dZ1An0FMLpwXWgDJFWjoUFp0fQ@mail.gmail.com>
Date:   Tue, 1 Dec 2020 10:46:32 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     yangyingliang@...wei.com
Cc:     Netdev <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, toshiaki.makita1@...il.com,
        rkovhaev@...il.com
Subject: Re: [PATCH net v2 1/2] wireguard: device: don't call free_netdev() in priv_destructor()

Hi Yang,

On Tue, Dec 1, 2020 at 10:31 AM Yang Yingliang <yangyingliang@...wei.com> wrote:
>
> After commit cf124db566e6 ("net: Fix inconsistent teardown and..."),
> priv_destruct() doesn't call free_netdev() in driver, we use
> dev->needs_free_netdev to indicate whether free_netdev() should be
> called on release path.
> This patch remove free_netdev() from priv_destructor() and set
> dev->needs_free_netdev to true.

For now, nack.

I remember when cf124db566e6 came out and carefully looking at the
construction of device.c in WireGuard. priv_destructor is only
assigned after register_device, with the various error paths in
wg_newlink responsible for cleaning up other earlier failures, and
trying to move to needs_free_netdev would have introduced more
complexity in this particular case, if my memory serves. I do not
think there's a memory leak here, and I worry about too hastily
changing the state machine "just because".

In other words, could you point out how to generate a memory leak? If
you're correct, then we can start dissecting and refactoring this. But
off the bat, I'm not sure I'm exactly seeing whatever you're seeing.

Jason