From: Dan Carpenter <dan.carpenter@oracle.com>
To: Colin King <colin.king@canonical.com>
Cc: Chas Williams <3chas3@gmail.com>,
linux-atm-general@lists.sourceforge.net, netdev@vger.kernel.org,
kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] atm: he: fix sign-extension overflow on large shift
Date: Wed, 16 Jan 2019 08:50:51 +0000 [thread overview]
Message-ID: <20190116085051.GC4482@kadam> (raw)
In-Reply-To: <20190115180338.32357-1-colin.king@canonical.com>
On Tue, Jan 15, 2019 at 06:03:38PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> Shifting the 1 by exp by an int can lead to sign-extension overlow when
> exp is 31 since 1 is an signed int and sign-extending this result to an
> unsigned long long will set the upper 32 bits. Fix this by shifting an
> unsigned long.
You could just cast it to unsigned.
rate_cps = (unsigned long long) (1U << exp) * (man + 512) >> 9;
I don't think it makes a difference at runtime because we just
pick buf = 4 either way...
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: Chas Williams <3chas3@gmail.com>,
linux-atm-general@lists.sourceforge.net, netdev@vger.kernel.org,
kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] atm: he: fix sign-extension overflow on large shift
Date: Wed, 16 Jan 2019 11:50:51 +0300 [thread overview]
Message-ID: <20190116085051.GC4482@kadam> (raw)
In-Reply-To: <20190115180338.32357-1-colin.king@canonical.com>
On Tue, Jan 15, 2019 at 06:03:38PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> Shifting the 1 by exp by an int can lead to sign-extension overlow when
> exp is 31 since 1 is an signed int and sign-extending this result to an
> unsigned long long will set the upper 32 bits. Fix this by shifting an
> unsigned long.
You could just cast it to unsigned.
rate_cps = (unsigned long long) (1U << exp) * (man + 512) >> 9;
I don't think it makes a difference at runtime because we just
pick buf = 4 either way...
regards,
dan carpenter
next prev parent reply other threads:[~2019-01-16 8:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-15 18:03 [PATCH] atm: he: fix sign-extension overflow on large shift Colin King
2019-01-16 8:50 ` Dan Carpenter [this message]
2019-01-16 8:50 ` Dan Carpenter
2019-01-17 19:47 ` David Miller
2019-01-17 19:47 ` David Miller
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=20190116085051.GC4482@kadam \
--to=dan.carpenter@oracle.com \
--cc=3chas3@gmail.com \
--cc=colin.king@canonical.com \
--cc=kernel-janitors@vger.kernel.org \
--cc=linux-atm-general@lists.sourceforge.net \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.