From: Dan Carpenter <dan.carpenter@oracle.com>
To: Colin King <colin.king@canonical.com>
Cc: Ian Abbott <abbotti@mev.co.uk>,
H Hartley Sweeten <hsweeten@visionengravers.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
devel@driverdev.osuosl.org, kernel-janitors@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] staging: comedi: dt2811: fix integer overflow in multiply
Date: Mon, 04 Feb 2019 07:48:20 +0000 [thread overview]
Message-ID: <20190204074820.GC2581@kadam> (raw)
In-Reply-To: <20190203112904.GA2563@kadam>
On Sun, Feb 03, 2019 at 02:29:04PM +0300, Dan Carpenter wrote:
> > diff --git a/drivers/staging/comedi/drivers/dt2811.c b/drivers/staging/comedi/drivers/dt2811.c
> > index 05207a519755..820e75f850ff 100644
> > --- a/drivers/staging/comedi/drivers/dt2811.c
> > +++ b/drivers/staging/comedi/drivers/dt2811.c
> > @@ -323,7 +323,8 @@ static unsigned int dt2811_ns_to_timer(unsigned int *nanosec,
> > for (_mult = 0; _mult <= 7; _mult++) {
> > unsigned int div = dt2811_clk_dividers[_div];
> > unsigned int mult = dt2811_clk_multipliers[_mult];
> > - unsigned long long divider = div * mult;
> > + unsigned long long divider > > + (unsigned long long)div * mult;
>
> The max "div" can be is 12. The max "mult" can be is 10,000,000. So
> this is a false positive because there is no overflow. The code is not
> complicated. Unfortunately, Smatch has the exact same problem...
Smatch actually parses this correctly, but I had a power failure over
the weekend that messed up my results.
regards,
dan carpenter
WARNING: multiple messages have this Message-ID (diff)
From: Dan Carpenter <dan.carpenter@oracle.com>
To: Colin King <colin.king@canonical.com>
Cc: Ian Abbott <abbotti@mev.co.uk>,
H Hartley Sweeten <hsweeten@visionengravers.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
devel@driverdev.osuosl.org, kernel-janitors@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] staging: comedi: dt2811: fix integer overflow in multiply
Date: Mon, 4 Feb 2019 10:48:20 +0300 [thread overview]
Message-ID: <20190204074820.GC2581@kadam> (raw)
In-Reply-To: <20190203112904.GA2563@kadam>
On Sun, Feb 03, 2019 at 02:29:04PM +0300, Dan Carpenter wrote:
> > diff --git a/drivers/staging/comedi/drivers/dt2811.c b/drivers/staging/comedi/drivers/dt2811.c
> > index 05207a519755..820e75f850ff 100644
> > --- a/drivers/staging/comedi/drivers/dt2811.c
> > +++ b/drivers/staging/comedi/drivers/dt2811.c
> > @@ -323,7 +323,8 @@ static unsigned int dt2811_ns_to_timer(unsigned int *nanosec,
> > for (_mult = 0; _mult <= 7; _mult++) {
> > unsigned int div = dt2811_clk_dividers[_div];
> > unsigned int mult = dt2811_clk_multipliers[_mult];
> > - unsigned long long divider = div * mult;
> > + unsigned long long divider =
> > + (unsigned long long)div * mult;
>
> The max "div" can be is 12. The max "mult" can be is 10,000,000. So
> this is a false positive because there is no overflow. The code is not
> complicated. Unfortunately, Smatch has the exact same problem...
Smatch actually parses this correctly, but I had a power failure over
the weekend that messed up my results.
regards,
dan carpenter
next prev parent reply other threads:[~2019-02-04 7:48 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-02 21:59 [PATCH] staging: comedi: dt2811: fix integer overflow in multiply Colin King
2019-02-02 21:59 ` Colin King
2019-02-03 11:29 ` Dan Carpenter
2019-02-03 11:29 ` Dan Carpenter
2019-02-04 7:48 ` Dan Carpenter [this message]
2019-02-04 7:48 ` Dan Carpenter
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