From: Andy Shevchenko <andy.shevchenko@gmail.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>,
Andy Shevchenko <andriy.shevchenko@linux.intel.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 10:03:15 +0300 [thread overview]
Message-ID: <CAHp75VdvZEhdmui0+1eS0BXvxBs60=uB0zOPex_TTDTrK7ewnQ@mail.gmail.com> (raw)
In-Reply-To: <20210513085227.54392-1-colin.king@canonical.com>
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.
> - map[index] |= v << offset;
> + map[index] |= (unsigned long)v << offset;
--
With Best Regards,
Andy Shevchenko
WARNING: multiple messages have this Message-ID (diff)
From: Andy Shevchenko <andy.shevchenko@gmail.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>,
Andy Shevchenko <andriy.shevchenko@linux.intel.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 10:03:15 +0300 [thread overview]
Message-ID: <CAHp75VdvZEhdmui0+1eS0BXvxBs60=uB0zOPex_TTDTrK7ewnQ@mail.gmail.com> (raw)
In-Reply-To: <20210513085227.54392-1-colin.king@canonical.com>
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.
> - map[index] |= v << offset;
> + map[index] |= (unsigned long)v << offset;
--
With Best Regards,
Andy Shevchenko
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linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-05-17 7:03 UTC|newest]
Thread overview: 18+ 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 8:52 ` Colin King
2021-05-13 9:10 ` David Laight
2021-05-13 9:10 ` David Laight
2021-05-17 7:04 ` Andy Shevchenko
2021-05-17 7:04 ` Andy Shevchenko
2021-05-14 5:37 ` Dan Carpenter
2021-05-14 5:37 ` Dan Carpenter
2021-05-17 7:07 ` Andy Shevchenko
2021-05-17 7:07 ` Andy Shevchenko
2021-05-17 13:36 ` Dan Carpenter
2021-05-17 13:36 ` Dan Carpenter
2021-05-17 13:49 ` Andy Shevchenko
2021-05-17 13:49 ` Andy Shevchenko
2021-05-17 7:03 ` Andy Shevchenko [this message]
2021-05-17 7:03 ` Andy Shevchenko
2021-05-17 7:32 ` Andy Shevchenko
2021-05-17 7:32 ` Andy Shevchenko
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