From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Colin King <colin.king@canonical.com>
Cc: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>,
Srinivas Neeli <srinivas.neeli@xilinx.com>,
Michal Simek <michal.simek@xilinx.com>,
Linus Walleij <linus.walleij@linaro.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
kernel-janitors <kernel-janitors@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH][next] gpio: xilinx: Fix potential integer overflow on shift of a u32 int
Date: Mon, 17 May 2021 10:32:56 +0300 [thread overview]
Message-ID: <YKIcKLLP1VXBhYfO@smile.fi.intel.com> (raw)
In-Reply-To: <CAHp75VdvZEhdmui0+1eS0BXvxBs60=uB0zOPex_TTDTrK7ewnQ@mail.gmail.com>
On Mon, May 17, 2021 at 10:03:15AM +0300, Andy Shevchenko wrote:
> On Thu, May 13, 2021 at 12:12 PM Colin King <colin.king@canonical.com> wrote:
> >
> > From: Colin Ian King <colin.king@canonical.com>
> >
> > The left shift of the u32 integer v is evaluated using 32 bit
> > arithmetic and then assigned to a u64 integer. There are cases
> > where v will currently overflow on the shift. Avoid this by
> > casting it to unsigned long (same type as map[]) before shifting
> > it.
> >
> > Addresses-Coverity: ("Unintentional integer overflow")
> > Fixes: 02b3f84d9080 ("gpio: xilinx: Switch to use bitmap APIs")
>
> No, it is a false positive,
>
> > const unsigned long offset = (bit % BITS_PER_LONG) & BIT(5);
>
> See above, offset is 0 when BITS_PER_LONG == 32 and 32 when it's equal to 64.
Should be read as "...and 0 or 32 when..."
> > - map[index] |= v << offset;
> > + map[index] |= (unsigned long)v << offset;
--
With Best Regards,
Andy Shevchenko
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prev parent reply other threads:[~2021-05-17 7:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-13 8:52 [PATCH][next] gpio: xilinx: Fix potential integer overflow on shift of a u32 int Colin King
2021-05-13 9:10 ` David Laight
2021-05-17 7:04 ` Andy Shevchenko
2021-05-14 5:37 ` Dan Carpenter
2021-05-17 7:07 ` Andy Shevchenko
2021-05-17 13:36 ` Dan Carpenter
2021-05-17 13:49 ` Andy Shevchenko
2021-05-17 7:03 ` Andy Shevchenko
2021-05-17 7:32 ` Andy Shevchenko [this message]
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