public inbox for linux-kernel@vger.kernel.org
 help / color / mirror / Atom feed
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Thor Thayer <thor.thayer@linux.intel.com>
Cc: linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH] i2c: altera: Use 64-bit arithmetic instead of 32-bit
Date: Mon, 10 Feb 2020 13:26:56 -0600	[thread overview]
Message-ID: <20200210192656.GA8412@embeddedor> (raw)

Add suffix ULL to constant 300 in order to avoid a potential integer
overflow and give the compiler complete information about the proper
arithmetic to use. Notice that this constant is being used in a context
that expects an expression of type u64, but it's currently evaluated
using 32-bit arithmetic.

Addresses-Coverity: 1458369 ("Unintentional integer overflow")
Fixes: 0560ad576268 ("i2c: altera: Add Altera I2C Controller driver")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/i2c/busses/i2c-altera.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-altera.c b/drivers/i2c/busses/i2c-altera.c
index 5255d3755411..526f453f0ff7 100644
--- a/drivers/i2c/busses/i2c-altera.c
+++ b/drivers/i2c/busses/i2c-altera.c
@@ -171,7 +171,8 @@ static void altr_i2c_init(struct altr_i2c_dev *idev)
 	/* SCL Low Time */
 	writel(t_low, idev->base + ALTR_I2C_SCL_LOW);
 	/* SDA Hold Time, 300ns */
-	writel(div_u64(300 * clk_mhz, 1000), idev->base + ALTR_I2C_SDA_HOLD);
+	writel(div_u64(300ULL * clk_mhz, 1000),
+	       idev->base + ALTR_I2C_SDA_HOLD);
 
 	/* Mask all master interrupt bits */
 	altr_i2c_int_enable(idev, ALTR_I2C_ALL_IRQ, false);
-- 
2.25.0


             reply	other threads:[~2020-02-10 19:44 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-10 19:26 Gustavo A. R. Silva [this message]
2020-02-10 20:42 ` [PATCH] i2c: altera: Use 64-bit arithmetic instead of 32-bit Thor Thayer
2020-02-11 11:44 ` David Laight

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=20200210192656.GA8412@embeddedor \
    --to=gustavo@embeddedor.com \
    --cc=linux-i2c@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=thor.thayer@linux.intel.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