From: Julia Lawall <julia.lawall@inria.fr>
To: Denis Efremov <efremov@linux.com>
Cc: cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org
Subject: Re: [Cocci] [PATCH] coccinelle: api: add kzfree script
Date: Thu, 4 Jun 2020 17:51:19 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.21.2006041749520.2577@hadrien> (raw)
In-Reply-To: <a188acce-348b-b106-9180-708c3050ef8d@linux.com>
On Thu, 4 Jun 2020, Denis Efremov wrote:
>
>
> On 6/4/20 5:15 PM, Julia Lawall wrote:
> > Did you try ... here but find that some subexpressions of E could be
> > modified in between?
>
> Yes, I tried to use "... when != E = E1 when != &E" and results were bad.
> Now, I've tried forall and when strict. Here are examples:
>
> // forall added
> // Works well, suitable for v2. One additional catch in w1 driver.
> @r depends on !patch && !(file in "lib/test_kasan.c") && !(file in "mm/slab_common.c") forall@
> expression *E; // pointer. Results are equal as if we use E.
> position p;
> @@
>
> * memset(E, 0, ...);
> ... when != E // Is it enough to match &E, E = E1?
Yes.
> * kfree(E)@p;
>
> //no forall, when strict
> //results are bad, too many false positives
> @r depends on !patch && !(file in "lib/test_kasan.c") && !(file in "mm/slab_common.c")@
> expression *E;
> position p;
> @@
>
> * memset(E, 0, ...);
> ... when != E // E is not enough here
> when strict
OK, it's reassonable.
> * kfree(E)@p;
>
> I guess that the difference is that "forall" requires that whole pattern should occur on
> every path, "when strict" states that kfree should be called on every path after memset.
> This results in missed uses of E in loops and under conditions. How can I state in this
> case that E should not occur at all (in all paths) in between memset, kfree even as a
> subexpression?
>
> // Doesn't work well
> ... when != E
> when != if (...) { ... E ... }
> when != for(...;...;...) { ... E ... }
Could you send an example of some C code on which the result is not
suitable?
julia
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next prev parent reply other threads:[~2020-06-04 15:51 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-04 14:08 [Cocci] [PATCH] coccinelle: api: add kzfree script Denis Efremov
2020-06-04 14:15 ` Julia Lawall
2020-06-04 15:39 ` Denis Efremov
2020-06-04 15:51 ` Julia Lawall [this message]
2020-06-04 17:22 ` Denis Efremov
2020-06-04 17:28 ` Julia Lawall
2020-06-04 16:27 ` Joe Perches
2020-06-04 17:30 ` Denis Efremov
2020-06-04 17:36 ` Joe Perches
2020-06-14 19:42 ` Denis Efremov
2020-06-14 20:01 ` Joe Perches
2020-06-15 12:03 ` Dan Carpenter
2020-06-15 13:51 ` Denis Efremov
2020-06-04 20:48 ` [Cocci] [PATCH v2] " Denis Efremov
2020-06-04 20:57 ` Julia Lawall
2020-06-04 21:03 ` Denis Efremov
2020-06-04 21:25 ` Denis Efremov
2020-06-06 8:16 ` Julia Lawall
2020-06-14 21:54 ` [Cocci] [PATCH v3] " Denis Efremov
2020-06-17 20:42 ` Julia Lawall
2020-06-17 21:42 ` Denis Efremov
2020-07-07 21:35 ` Julia Lawall
2020-07-17 11:57 ` [Cocci] [PATCH v4] " Denis Efremov
2020-07-17 20:39 ` Julia Lawall
2020-08-10 23:45 ` Eric Biggers
2020-08-11 7:12 ` Denis Efremov
2020-08-11 7:49 ` [Cocci] [PATCH] coccinelle: api: update kzfree script to kfree_sensitive Denis Efremov
2020-08-26 8:12 ` Denis Efremov
2020-09-12 15:08 ` Julia Lawall
2020-06-04 15:20 [Cocci] [PATCH] coccinelle: api: add kzfree script Markus Elfring
2020-06-04 15:56 ` Julia Lawall
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