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Groups > linux.kernel > #1299338
| From | Andrzej Hajda <a.hajda@samsung.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v4] coccinelle: tests: unsigned value cannot be lesser than zero |
| Date | 2015-12-30 13:40 +0100 |
| Message-ID | <qLocN-6Df-3@gated-at.bofh.it> (permalink) |
| References | <qLmNH-5Po-3@gated-at.bofh.it> <qLn73-5Wu-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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[PATCH v4] coccinelle: tests: unsigned value cannot be lesser than zero Andrzej Hajda <a.hajda@samsung.com> - 2015-12-30 12:10 +0100
Re: [PATCH v4] coccinelle: tests: unsigned value cannot be lesser than zero Julia Lawall <julia.lawall@lip6.fr> - 2015-12-30 12:30 +0100
Re: [PATCH v4] coccinelle: tests: unsigned value cannot be lesser than zero Andrzej Hajda <a.hajda@samsung.com> - 2015-12-30 13:40 +0100
[PATCH v5] coccinelle: tests: unsigned value cannot be lesser than zero Andrzej Hajda <a.hajda@samsung.com> - 2015-12-30 14:30 +0100
Re: [PATCH v5] coccinelle: tests: unsigned value cannot be lesser than zero Julia Lawall <julia.lawall@lip6.fr> - 2015-12-30 15:10 +0100
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