linux-kernel - Re: [PATCH V3] binder: ipc namespace support for android binder

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: <20181109182654.ojzc7wae3jcivlup@linux-r8p5>
Date:   Fri, 9 Nov 2018 10:26:54 -0800
From:   Davidlohr Bueso <dave@...olabs.net>
To:     "chouryzhou(??????)" <chouryzhou@...cent.com>
Cc:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "arve@...roid.com" <arve@...roid.com>,
        "tkjos@...roid.com" <tkjos@...roid.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3] binder: ipc namespace support for android binder

On Thu, 08 Nov 2018, chouryzhou(??????) wrote:

>+#ifdef CONFIG_ANDROID_BINDER_IPC
>+       /* next fields are for binder */
>+       struct mutex      binder_procs_lock;
>+       struct hlist_head binder_procs;
>+       struct hlist_head binder_contexts;
>+#endif

Now, I took a look at how the binder_procs list is used; and no, what
follows isn't really related to this patch, but a general observation.

I think that a mutex is also an overkill and you might wanna replace it
with a spinlock/rwlock. Can anything block while holding the binder_procs_lock?
I don't see anything... you mainly need it for consulting the hlist calling
print_binder_proc[_stat]() - which will take the proc->inner_lock anyway, so
no blocking there. Also, if this is perhaps because of long hold times, dunno,
the rb_first_cached primitive might reduce some of it, although I don't know
how big the rbtrees in binder can get and if it matters at all.

Anyway, that said and along with addressing Todd's comments, the ipc/ bits look
good. Feel free to add my:

Reviewed-by: Davidlohr Bueso <dave@...olabs.net>

Thanks,
Davidlohr