netdev - Re: [Linux-kernel-mentees] [PATCH net] rds: Prevent kernel-infoleak in rds_notify_queue

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Message-ID: <20200803230627.GQ24045@ziepe.ca>
Date:   Mon, 3 Aug 2020 20:06:27 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Joe Perches <joe@...ches.com>
Cc:     Leon Romanovsky <leon@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peilin Ye <yepeilin.cs@...il.com>,
        Santosh Shilimkar <santosh.shilimkar@...cle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Arnd Bergmann <arnd@...db.de>,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        netdev@...r.kernel.org, linux-rdma@...r.kernel.org,
        rds-devel@....oracle.com, linux-kernel@...r.kernel.org
Subject: Re: [Linux-kernel-mentees] [PATCH net] rds: Prevent kernel-infoleak
 in rds_notify_queue_get()

On Sun, Aug 02, 2020 at 03:45:40PM -0700, Joe Perches wrote:
> On Sun, 2020-08-02 at 19:28 -0300, Jason Gunthorpe wrote:
> > On Sun, Aug 02, 2020 at 03:23:58PM -0700, Joe Perches wrote:
> > > On Sun, 2020-08-02 at 19:10 -0300, Jason Gunthorpe wrote:
> > > > On Sat, Aug 01, 2020 at 08:38:33AM +0300, Leon Romanovsky wrote:
> > > > 
> > > > > I'm using {} instead of {0} because of this GCC bug.
> > > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53119
> > > > 
> > > > This is why the {} extension exists..
> > > 
> > > There is no guarantee that the gcc struct initialization {}
> > > extension also zeros padding.
> >
> > We just went over this. Yes there is, C11 requires it.
> 
> c11 is not c90.  The kernel uses c90.

The kernel already relies on a lot of C11/C99 features and
behaviors. For instance Linus just bumped the minimum compiler version
so that C11's _Generic is usable.

Why do you think this particular part of C11 shouldn't be relied on?

Jason