From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Rohit Sarkar <rohitsarkar5398@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@intel.com>,
linux-iio <linux-iio@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jonathan Cameron <jic23@kernel.org>,
dragos.bogdan@analog.com, Lars-Peter Clausen <lars@metafoo.de>,
Michael Hennerich <Michael.Hennerich@analog.com>,
Stefan Popa <stefan.popa@analog.com>,
Hartmut Knaack <knaack.h@gmx.de>,
Peter Meerwald <pmeerw@pmeerw.net>
Subject: Re: [PATCH] iio: gyro: adis16136: use scnprintf instead of snprintf
Date: Sun, 22 Mar 2020 12:27:27 +0200 [thread overview]
Message-ID: <CAHp75VddtJs1ZCk1XAZ2WJLhWQDcVwiiN5gDpK9oYPEOS=c_ZQ@mail.gmail.com> (raw)
In-Reply-To: <5e77017a.1c69fb81.dc341.8ab9@mx.google.com>
On Sun, Mar 22, 2020 at 8:11 AM Rohit Sarkar <rohitsarkar5398@gmail.com> wrote:
>
> On Sun, Mar 22, 2020 at 02:25:42AM +0200, Andy Shevchenko wrote:
> > On Wed, Mar 18, 2020 at 08:25:22PM +0530, Rohit Sarkar wrote:
> > > scnprintf returns the actual number of bytes written into the buffer as
> > > opposed to snprintf which returns the number of bytes that would have
> > > been written if the buffer was big enough. Using the output of snprintf
> > > may lead to difficult to detect bugs.
> >
> > Nice. Have you investigate the code?
> >
> > > @@ -96,7 +96,7 @@ static ssize_t adis16136_show_serial(struct file *file,
> > > if (ret)
> > > return ret;
> > >
> > > - len = snprintf(buf, sizeof(buf), "%.4x%.4x%.4x-%.4x\n", lot1, lot2,
> > > + len = scnprintf(buf, sizeof(buf), "%.4x%.4x%.4x-%.4x\n", lot1, lot2,
> > > lot3, serial);
> > >
> > > return simple_read_from_buffer(userbuf, count, ppos, buf, len);
> >
> > The buffer size is 20, the pattern size I count to 19. Do you think snprintf()
> > can fail?
> That might be the case, but IMO using scnprintf can be considered as a
> best practice. There is no overhead with this change and further if the
> pattern is changed by someone in the future they might overlook the
> buffersize
If we cut the string above we will give wrong information to the user space.
I think scnprintf() change is a noise and does not improve the situation anyhow.
So, when anybody modifying such code the test should be performed.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2020-03-22 10:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-18 14:55 [PATCH] iio: gyro: adis16136: use scnprintf instead of snprintf Rohit Sarkar
2020-03-22 0:25 ` Andy Shevchenko
2020-03-22 6:11 ` Rohit Sarkar
2020-03-22 10:27 ` Andy Shevchenko [this message]
2020-03-23 15:04 ` David Laight
2020-03-23 16:05 ` 'Andy Shevchenko'
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='CAHp75VddtJs1ZCk1XAZ2WJLhWQDcVwiiN5gDpK9oYPEOS=c_ZQ@mail.gmail.com' \
--to=andy.shevchenko@gmail.com \
--cc=Michael.Hennerich@analog.com \
--cc=andriy.shevchenko@intel.com \
--cc=dragos.bogdan@analog.com \
--cc=jic23@kernel.org \
--cc=knaack.h@gmx.de \
--cc=lars@metafoo.de \
--cc=linux-iio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pmeerw@pmeerw.net \
--cc=rohitsarkar5398@gmail.com \
--cc=stefan.popa@analog.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).