From: Adrian Hunter <adrian.hunter@intel.com>
To: Haibo Chen <haibo.chen@nxp.com>, ulf.hansson@linaro.org
Cc: linux-mmc@vger.kernel.org
Subject: Re: [PATCH] mmc: sdhci: cast unsigned int to unsigned long long to avoid unexpeted error
Date: Fri, 14 Oct 2016 12:12:27 +0300 [thread overview]
Message-ID: <cd546cd4-e64f-1b86-1cae-08b89dabc410@intel.com> (raw)
In-Reply-To: <3603c63f-f007-12cc-677b-f39924628335@intel.com>
On 13/09/16 11:36, Adrian Hunter wrote:
> On 13/09/16 10:06, Haibo Chen wrote:
>> Potentially overflowing expression 1000000 * data->timeout_clks with
>> type unsigned int is evaluated using 32-bit arithmetic, and then used
>> in a context that expects an expression of type unsigned long long.
>>
>> To avoid overflow, cast 1000000U to type unsigned long long.
>> Special thanks to coverity <http://www.coverity.com>
>
> Let's leave out the web link - it is enough to say it was found with Coverity.
>
>>
>> Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Do you plan to re-submit this?
>
> Needs a fixes tag and cc stable.
>
>> ---
>> drivers/mmc/host/sdhci.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index 4805566..0e9f495 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -687,7 +687,7 @@ static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_command *cmd)
>> * host->clock is in Hz. target_timeout is in us.
>> * Hence, us = 1000000 * cycles / Hz. Round up.
>> */
>> - val = 1000000 * data->timeout_clks;
>> + val = (unsigned long long)1000000 * data->timeout_clks;
>
> Please use 1000000ULL instead of a cast.
>
>> if (do_div(val, host->clock))
>> target_timeout++;
>> target_timeout += val;
>>
>
>
next prev parent reply other threads:[~2016-10-14 9:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-13 7:06 [PATCH] mmc: sdhci: cast unsigned int to unsigned long long to avoid unexpeted error Haibo Chen
2016-09-13 8:36 ` Adrian Hunter
2016-10-14 9:12 ` Adrian Hunter [this message]
2016-10-14 9:53 ` Bough Chen
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