From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Tue, 26 Feb 2019 08:31:09 +1100
From: "Tobin C. Harding" <me@tobin.cc>
Subject: Re: [PATCH v2 1/1] lib/string: Add strscpy_pad() function
Message-ID: <20190225213109.GB5177@eros.localdomain>
References: <20190225041534.27186-1-tobin@kernel.org>
 <20190225041534.27186-2-tobin@kernel.org>
 <CAHp75Vfq5KQupcyx_84YcSOQ8mvNDvFE3R20KdyLEqEz74p3OQ@mail.gmail.com>
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In-Reply-To: <CAHp75Vfq5KQupcyx_84YcSOQ8mvNDvFE3R20KdyLEqEz74p3OQ@mail.gmail.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: "Tobin C. Harding" <tobin@kernel.org>, Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Randy Dunlap <rdunlap@infradead.org>, Rasmus Villemoes <linux@rasmusvillemoes.dk>, Stephen Rothwell <sfr@canb.auug.org.au>, Andy Lutomirski <luto@amacapital.net>, Daniel Micay <danielmicay@gmail.com>, Arnd Bergmann <arnd@arndb.de>, Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>, "Gustavo A. R. Silva" <gustavo@embeddedor.com>, Shuah Khan <shuah@kernel.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Alexander Shishkin <alexander.shishkin@linux.intel.com>, Kernel Hardening <kernel-hardening@lists.openwall.com>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
List-ID: <kernel-hardening.lists.openwall.com>

On Mon, Feb 25, 2019 at 10:19:47AM +0200, Andy Shevchenko wrote:
> On Mon, Feb 25, 2019 at 6:17 AM Tobin C. Harding <tobin@kernel.org> wrote:
> >
> > We have a function to copy strings safely and we have a function to copy
> > strings and zero the tail of the destination (if source string is
> > shorter than destination buffer) but we do not have a function to do
> > both at once.  This means developers must write this themselves if they
> > desire this functionality.  This is a chore, and also leaves us open to
> > off by one errors unnecessarily.
> >
> > Add a function that calls strscpy() then memset()s the tail to zero if
> > the source string is shorter than the destination buffer.
> >
> > Add test module for the new code.
> 
> > --- /dev/null
> > +++ b/lib/test_strscpy.c
> > @@ -0,0 +1,175 @@
> 
> > +// SPDX-License-Identifier: GPL-2.0
> 
> > +MODULE_LICENSE("GPL");
> 
> License mismatch.

Thanks, will re-spin with 

  // SPDX-License-Identifier: GPL-2.0+

> Do we need a separate module for this test?

Separate as in not in lib/test_string.h?  I intend on moving the test
into that file once I've done some cleanup in tools/testing/selftest/lib/

I also tried to do this without using a module using
tools/testing/selftest/kselftest_harness.h but I could not get the
compiler to see read the patched version of
linux/include/linux/string.h?

Related question if you feel like answering it; why are test modules for
lib/ in lib/ and not in tools/testing/?

Very much open to suggestions on current best practices for kernel testing.

thanks,
Tobin.