linux-kernel - Re: [PATCH 5/6] lib: Fix function documentation for strncpy_from

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAGXu5j+da7frEM62vV+WZUTDSuNnUQCxEc7FCL01=jtqDAUb9Q@mail.gmail.com>
Date:   Thu, 21 Feb 2019 14:52:22 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Jann Horn <jannh@...gle.com>
Cc:     "Tobin C. Harding" <tobin@...nel.org>,
        Shuah Khan <shuah@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>,
        kernel list <linux-kernel@...r.kernel.org>,
        Andy Lutomirski <luto@...capital.net>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Daniel Micay <danielmicay@...il.com>
Subject: Re: [PATCH 5/6] lib: Fix function documentation for strncpy_from_user

On Thu, Feb 21, 2019 at 6:28 AM Jann Horn <jannh@...gle.com> wrote:
> On Thu, Feb 21, 2019 at 2:05 AM Kees Cook <keescook@...omium.org> wrote:
> > On Mon, Feb 18, 2019 at 4:52 PM Jann Horn <jannh@...gle.com> wrote:
> > > AFAICS the byte_at_a_time loop exits when max==0 is reached, and then
> > > if `res >= count` (in other words, if we've copied as many bytes as
> > > requested, haven't encountered a null byte so far, and haven't reached
> > > the end of the address space), we return `res`, which is the same as
> > > `count`. Are you sure?
> >
> > Oh, whew, there is only 1 arch-specific implementation of this. I
> > thought you meant there was multiple implementations.
>
> Not sure what you're talking about. Are you talking about
> implementations of strncpy_from_user()?

Ah, I used a bad match. But it seems it's only about half (and not
x86, arm, powerpc).

-- 
Kees Cook