Messages in this thread |  | | Date | Tue, 30 Jan 2018 02:51:41 -0600 | From | "Gustavo A. R. Silva" <> | Subject | Re: [PATCH 8/8] platform: vivid-cec: fix potential integer overflow in vivid_cec_pin_adap_events |
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Hi Hans,
Quoting Hans Verkuil <hverkuil@xs4all.nl>:
> Hi Gustavo, > > On 01/30/2018 01:33 AM, Gustavo A. R. Silva wrote: >> Cast len to const u64 in order to avoid a potential integer >> overflow. This variable is being used in a context that expects >> an expression of type const u64. >> >> Addresses-Coverity-ID: 1454996 ("Unintentional integer overflow") >> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> >> --- >> drivers/media/platform/vivid/vivid-cec.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/media/platform/vivid/vivid-cec.c >> b/drivers/media/platform/vivid/vivid-cec.c >> index b55d278..30240ab 100644 >> --- a/drivers/media/platform/vivid/vivid-cec.c >> +++ b/drivers/media/platform/vivid/vivid-cec.c >> @@ -83,7 +83,7 @@ static void vivid_cec_pin_adap_events(struct >> cec_adapter *adap, ktime_t ts, >> if (adap == NULL) >> return; >> ts = ktime_sub_us(ts, (CEC_TIM_START_BIT_TOTAL + >> - len * 10 * CEC_TIM_DATA_BIT_TOTAL)); >> + (const u64)len * 10 * CEC_TIM_DATA_BIT_TOTAL)); > > This makes no sense. Certainly the const part is pointless. And given that > len is always <= 16 there definitely is no overflow. >
Yeah, I understand your point and I know there is no chance of an overflow in this particular case.
> I don't really want this cast in the code. > > Sorry, >
I'm working through all the Linux kernel Coverity reports, and I thought of sending a patch for this because IMHO it doesn't hurt to give the compiler complete information about the arithmetic in which an expression is intended to be evaluated.
I agree that the _const_ part is a bit odd. What do you think about the cast to u64 alone?
I appreciate your feedback.
Thanks -- Gustavo
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