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From: "Tobin C. Harding" <me@tobin.cc>
To: Jann Horn <jannh@google.com>
Cc: "Tobin C. Harding" <tobin@kernel.org>,
	Kees Cook <keescook@chromium.org>, Shuah Khan <shuah@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	kernel list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 6/6] lib: Add function strscpy_from_user()
Date: Wed, 20 Feb 2019 08:53:45 +1100	[thread overview]
Message-ID: <20190219215345.GB16094@eros.localdomain> (raw)
In-Reply-To: <CAG48ez1n=+GsvhMxHhxL=EBxD6VEqopdLRPcEAff9vrP3+a30g@mail.gmail.com>

On Tue, Feb 19, 2019 at 03:12:33AM +0100, Jann Horn wrote:
> On Tue, Feb 19, 2019 at 12:25 AM Tobin C. Harding <tobin@kernel.org> wrote:
> > Currently we have strncpy_from_userspace().  If the user string is
> > longer than the destination kernel buffer we get an error code -EFAULT.
> > We are unable to recover from here because this is the same error
> > returned if the access to userspace fails totally.
> >
> > There is no reason we cannot continue execution with the user string
> > truncated.
> >
> > Add a function strscpy_from_user() that guarantees the string written is
> > null-terminated.  If user string is longer than destination buffer
> > truncates the string.  Returns the number of characters written
> > excluding the null-terminator.
> >
> > Signed-off-by: Tobin C. Harding <tobin@kernel.org>
> > ---
> >  lib/strncpy_from_user.c | 43 +++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 43 insertions(+)
> >
> > diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
> > index 11fe9a4a00fd..6bd603ccec7a 100644
> > --- a/lib/strncpy_from_user.c
> > +++ b/lib/strncpy_from_user.c
> 
> This file is only built when CONFIG_GENERIC_STRNCPY_FROM_USER is set.
> Some architectures have their own versions of strncpy_from_user() and
> don't set that, so on those architectures, your code wouldn't be built
> into the kernel.

thanks!  Dropping *_from_user() stuff from set.

	Tobin

  reply	other threads:[~2019-02-19 21:53 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-18 23:23 [PATCH 0/6] lib: Add safe string funtions Tobin C. Harding
2019-02-18 23:23 ` [PATCH 1/6] lib/string: Enable string selftesting Tobin C. Harding
2019-02-19 10:55   ` Andy Shevchenko
2019-02-19 21:55     ` Tobin C. Harding
2019-02-20 10:49       ` Andy Shevchenko
2019-02-20 23:58       ` Kees Cook
2019-02-20 23:57   ` Kees Cook
2019-02-21  5:16     ` Tobin C. Harding
2019-02-18 23:23 ` [PATCH 2/6] lib/string: Fix erroneous 'overflow' documentation Tobin C. Harding
2019-02-21  0:02   ` Kees Cook
2019-02-21  5:17     ` Tobin C. Harding
2019-02-18 23:23 ` [PATCH 3/6] lib/string: Use correct docstring format Tobin C. Harding
2019-02-21  0:07   ` Kees Cook
2019-02-21  4:14     ` Randy Dunlap
2019-02-21  5:27       ` Kees Cook
2019-02-18 23:23 ` [PATCH 4/6] lib/string: Add string copy/zero function Tobin C. Harding
2019-02-21  0:48   ` Kees Cook
2019-02-21  5:20     ` Tobin C. Harding
2019-02-21 12:02     ` Andy Shevchenko
2019-02-25 20:09     ` Tobin C. Harding
2019-02-18 23:23 ` [PATCH 5/6] lib: Fix function documentation for strncpy_from_user Tobin C. Harding
2019-02-19  0:51   ` Jann Horn
2019-02-19 21:52     ` Tobin C. Harding
2019-02-21  1:05     ` Kees Cook
2019-02-21  5:24       ` Tobin C. Harding
2019-02-21  6:02         ` Kees Cook
2019-02-21 14:58           ` Rasmus Villemoes
2019-02-21 23:03             ` Kees Cook
2019-02-25 15:41               ` Rasmus Villemoes
2019-02-21 16:06           ` Jann Horn
2019-02-21 23:14             ` Kees Cook
2019-02-21 20:26           ` Stephen Rothwell
2019-02-21 23:16             ` Kees Cook
2019-02-21 14:28       ` Jann Horn
2019-02-21 22:52         ` Kees Cook
2019-02-18 23:23 ` [PATCH 6/6] lib: Add function strscpy_from_user() Tobin C. Harding
2019-02-19  2:09   ` Jann Horn
2019-02-19  2:12   ` Jann Horn
2019-02-19 21:53     ` Tobin C. Harding [this message]
2019-02-20 23:31 ` [PATCH 0/6] lib: Add safe string funtions Kees Cook
2019-02-21  5:15   ` Tobin C. Harding

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