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Date:   Sun, 26 Aug 2018 22:00:46 -0400 (EDT)
From:   Julia Lawall <julia.lawall@lip6.fr>
To:     Al Viro <viro@ZenIV.linux.org.uk>
cc:     Joe Perches <joe@perches.com>, Julia Lawall <julia.lawall@lip6.fr>,
        Kees Cook <keescook@chromium.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Jamal Hadi Salim <jhs@mojatatu.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        Jiri Pirko <jiri@resnulli.us>,
        "David S. Miller" <davem@davemloft.net>,
        Network Development <netdev@vger.kernel.org>
Subject: Re: [PATCH] net: sched: Fix memory exposure from short TCA_U32_SEL
In-Reply-To: <20180826224322.GX6515@ZenIV.linux.org.uk>
Message-ID: <alpine.DEB.2.21.1808262159430.2528@hadrien>
References: <20180826055801.GA42063@beast> <20180826061534.GT6515@ZenIV.linux.org.uk> <CAGXu5jK7VzayzZTcxgZBf-+YHWO+Hv7s8utj2rzTc3gFtA8pFQ@mail.gmail.com> <20180826173236.GU6515@ZenIV.linux.org.uk> <d31fe59160e0b7d40e09536a3c74619ebb1f3b13.camel@perches.com>
 <20180826212421.GW6515@ZenIV.linux.org.uk> <eca48539a3dede3bfaed9ab9a6c06794cf8160e0.camel@perches.com> <20180826224322.GX6515@ZenIV.linux.org.uk>
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On Sun, 26 Aug 2018, Al Viro wrote:

> On Sun, Aug 26, 2018 at 03:26:54PM -0700, Joe Perches wrote:
> > On Sun, 2018-08-26 at 22:24 +0100, Al Viro wrote:
> > > On Sun, Aug 26, 2018 at 11:57:57AM -0700, Joe Perches wrote:
> > >
> > > > > That, BTW, is why I hate the use of sizeof(*p) in kmalloc, etc.
> > > > > arguments.  typeof is even worse in that respect.
> > > >
> > > > True.  Semantic searches via tools like coccinelle could help here
> > > > but those searches are quite a bit slower than straightforward greps.
> > >
> > > Those searches are .config-sensitive as well, which can be much more
> > > unpleasant than being slow...
> >
> > Are they?  Julia?
>
> They work pretty much on preprocessor output level; if something it ifdef'ed
> out on given config, it won't be seen...

Coccinelle doesn't care what is ifdef'd out.  It only misses the things it
can't parse.  Very strange ifdefs could indeed cause that, but it should
be a minor problem.

julia