From: Julia Lawall <julia.lawall@inria.fr>
To: Denis Efremov <efremov@linux.com>
Cc: cocci@systeme.lip6.fr
Subject: Re: [Cocci] Backward compatibility issue
Date: Sat, 13 Feb 2021 08:46:11 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.22.394.2102130843330.2720@hadrien> (raw)
In-Reply-To: <f7c2e83e-0cdd-d414-0fb1-e57cd380dce7@linux.com>
On Fri, 12 Feb 2021, Denis Efremov wrote:
>
>
> On 2/12/21 5:04 PM, Julia Lawall wrote:
> >
> >
> > On Thu, 11 Feb 2021, Denis Efremov wrote:
> >
> >> Hi, one of my patterns started to fail tests on latest coccinelle.
> >> I've bisected the commit that introduces "error". It's:
> >> commit db60e916633d2cb3ae31140364783fdf85ed10f4
> >> "make information about SmPL iterator and declarer names available to the C parser"
> >>
> >> To reproduce the error:
> >> $ cd linux
> >> $ git checkout 5b01014759991887b1e450c9def01e58c02ab81b
> >> $ wget https://raw.githubusercontent.com/evdenis/cvehound/master/cvehound/cve/CVE-2016-9793.cocci
> >> $ spatch -D detect --cocci-file CVE-2016-9793.cocci net/core/sock.c
> >> # spatch before db60e916633d2cb3ae31140364783fdf85ed10f4 will find the match
> >> net/core/sock.c:718:16-17: ERROR: CVE-2016-9793
> >> net/core/sock.c:754:16-17: ERROR: CVE-2016-9793
> >> ...
> >> # spatch >= db60e916633d2cb3ae31140364783fdf85ed10f4 will not match the same code
> >
> > If you change typedef u32 to symbol u32, it should be good. It is no use
> > to Coccinelle to know that u32 is a typedef in this code.
>
> After changing typedef to symbol, git version starts to match the code,
> but coccinelle 1.0.8 starts to fail the detection.
Strange, I'll check.
> Well, this doesn't
> solve the problem for me.
>
> What's the difference between symbol and typedef? How can I understand
> when to use one or another?
Typedef allows the thing to be used as a type. But in semantic patch that
oyu have, there is no way for Coccinelle to know that u32 is being used as
a type. It's just the argument to a macro. It could be any identifier.
Symbol just means "this is an identifier I want to match exactly, and I
don't want the semantic patch parser to ask me if it should be a
metavariable". It actually has no impact on the matching process.
julia
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prev parent reply other threads:[~2021-02-13 7:46 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-11 12:09 [Cocci] Backward compatibility issue Denis Efremov
2021-02-11 13:46 ` Julia Lawall
2021-02-12 14:04 ` Julia Lawall
2021-02-12 20:18 ` Denis Efremov
2021-02-13 7:46 ` Julia Lawall [this message]
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