From: Andrzej Hajda <a.hajda@samsung.com>
To: Julia Lawall <julia.lawall@lip6.fr>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Gilles Muller <Gilles.Muller@lip6.fr>,
Nicolas Palix <nicolas.palix@imag.fr>,
Michal Marek <mmarek@suse.com>,
open list <linux-kernel@vger.kernel.org>,
"moderated list:COCCINELLE/Semantic Patches (SmPL)"
<cocci@systeme.lip6.fr>
Subject: Re: [PATCH v4] coccinelle: tests: unsigned value cannot be lesser than zero
Date: Wed, 30 Dec 2015 13:33:30 +0100 [thread overview]
Message-ID: <5683CF1A.1030109@samsung.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1512301227090.2048@localhost6.localdomain6>
On 12/30/2015 12:29 PM, Julia Lawall wrote:
>
>
> On Wed, 30 Dec 2015, Andrzej Hajda wrote:
>
>> Unsigned expressions cannot be lesser than zero. Presence of comparisons
>> 'unsigned (<|<=|>|>=) 0' often indicates a bug, usually wrong type of variable.
>> The patch beside finding such comparisons tries to eliminate false positives,
>> mainly by bypassing range checks.
>>
>> gcc can detect such comparisons also using -Wtype-limits switch, but it warns
>> also in correct cases, making too much noise.
>>
>> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
>> ---
>> v4: added range check detection, added full check in case value holds a result
>> of signed function
>> v3: added bool type
>> v2: added --all-includes option
>> ---
>> Hi Julia,
>>
>> This version adds range check detection, as a result false positives are almost
>> fully eliminated. Most of kernel patches have been already sent and accepted,
>> but some new bugs appeared since then. I will prepare bugfixes soon.
>>
>> I have enountered one issue, the patch does not detect range check in
>> drivers/leds/leds-tca6507.c:716:
>> if (ret != 0 || reg < 0 || reg >= NUM_LEDS)
>>
>> Simplified check, responsible for detectin range checks:
>> @@
>> expression v, c;
>> @@
>>
>> * (\( v < 0 \| v <= 0 \)) || (\( v >= c \| v > c \))
>>
>> Is it a bug or expected behavior? Maybe consequence of left-to-right associativity?
>
> Yes, it would be an associativity problem. Could you try with || ...
> added to the right end of your pattern? That should allow it to let the
> disjunctions appear anywhere at top level, but I'm not sure to what extent
> it works when the pattern already contains a disjunction. You could also
> try
>
> A || ... || B || ...
>
"A || ... || B" does the trick.
Regards
Andrzej
next prev parent reply other threads:[~2015-12-30 12:33 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-30 11:06 [PATCH v4] coccinelle: tests: unsigned value cannot be lesser than zero Andrzej Hajda
2015-12-30 11:29 ` Julia Lawall
2015-12-30 12:33 ` Andrzej Hajda [this message]
2015-12-30 13:25 ` [PATCH v5] " Andrzej Hajda
2015-12-30 14:06 ` Julia Lawall
2016-01-04 7:45 ` [PATCH v6] " Andrzej Hajda
2016-01-05 12:59 ` Geyslan G. Bem
2016-01-05 13:02 ` Julia Lawall
2016-01-05 14:10 ` Geyslan G. Bem
2016-01-05 16:48 ` Geyslan G. Bem
2016-01-05 13:49 ` Andrzej Hajda
2016-01-05 14:18 ` Geyslan G. Bem
2016-01-05 14:17 ` Julia Lawall
2016-01-05 14:29 ` Andrzej Hajda
2016-01-07 9:36 ` [PATCH v7] " Andrzej Hajda
2016-01-07 11:35 ` Julia Lawall
2016-01-07 14:37 ` Michal Marek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5683CF1A.1030109@samsung.com \
--to=a.hajda@samsung.com \
--cc=Gilles.Muller@lip6.fr \
--cc=b.zolnierkie@samsung.com \
--cc=cocci@systeme.lip6.fr \
--cc=julia.lawall@lip6.fr \
--cc=linux-kernel@vger.kernel.org \
--cc=m.szyprowski@samsung.com \
--cc=mmarek@suse.com \
--cc=nicolas.palix@imag.fr \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).