From: Wolfram Sang <wsa@kernel.org>
To: Colin King <colin.king@canonical.com>, qii.wang@mediatek.com
Cc: Matthias Brugger <matthias.bgg@gmail.com>,
linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org,
kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH][next] i2c: mediatek: fix integer overflow on an integer multiplication
Date: Mon, 18 May 2020 18:59:28 +0200 [thread overview]
Message-ID: <20200518165928.GA5109@ninjato> (raw)
In-Reply-To: <20200518165529.57821-1-colin.king@canonical.com>
[-- Attachment #1: Type: text/plain, Size: 1344 bytes --]
On Mon, May 18, 2020 at 05:55:29PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> Currently the calculation of sample_ns is using a 32 bit integer
> multiplication and can potentially overflow. Fix this by making the
> constant a long long to use a 64 bit multiply and hence
> avoid an overflow.
>
> Addresses-Coverity: ("Unintentional integer overflow")
> Fixes: 5f1ae73d538a ("i2c: mediatek: Add i2c ac-timing adjust support")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
CCing the patch author.
> ---
> drivers/i2c/busses/i2c-mt65xx.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
> index 702061805925..c93492b997ce 100644
> --- a/drivers/i2c/busses/i2c-mt65xx.c
> +++ b/drivers/i2c/busses/i2c-mt65xx.c
> @@ -551,7 +551,7 @@ static int mtk_i2c_check_ac_timing(struct mtk_i2c *i2c,
> const struct i2c_spec_values *spec;
> unsigned int su_sta_cnt, low_cnt, high_cnt, max_step_cnt;
> unsigned int sda_max, sda_min, clk_ns, max_sta_cnt = 0x3f;
> - long long sample_ns = (1000000000 * (sample_cnt + 1)) / clk_src;
> + long long sample_ns = (1000000000LL * (sample_cnt + 1)) / clk_src;
>
> if (!i2c->dev_comp->timing_adjust)
> return 0;
> --
> 2.25.1
>
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
next prev parent reply other threads:[~2020-05-18 16:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-18 16:55 [PATCH][next] i2c: mediatek: fix integer overflow on an integer multiplication Colin King
2020-05-18 16:59 ` Wolfram Sang [this message]
2020-05-18 17:11 ` Joe Perches
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200518165928.GA5109@ninjato \
--to=wsa@kernel.org \
--cc=colin.king@canonical.com \
--cc=kernel-janitors@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-i2c@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mediatek@lists.infradead.org \
--cc=matthias.bgg@gmail.com \
--cc=qii.wang@mediatek.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).