linux-kernel - Re: [PATCH] mips: vdso: conditionalize 32-bit time functions on COMPAT_32BIT

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: <CAK8P3a0NBuqDX63+920q7Q+yO2xCoSd0O7xUDJv6BBoco2kVOg@mail.gmail.com>
Date:   Mon, 30 Dec 2019 16:47:37 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "open list:BROADCOM NVRAM DRIVER" <linux-mips@...r.kernel.org>,
        Paul Burton <paulburton@...nel.org>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Christian Brauner <christian.brauner@...onical.com>
Subject: Re: [PATCH] mips: vdso: conditionalize 32-bit time functions on COMPAT_32BIT_TIME

On Mon, Dec 30, 2019 at 4:39 PM Jason A. Donenfeld <Jason@...c4.com> wrote:
>
> On Mon, Dec 30, 2019 at 4:37 PM Arnd Bergmann <arnd@...db.de> wrote:
> >
> > On Mon, Dec 30, 2019 at 3:37 PM Jason A. Donenfeld <Jason@...c4.com> wrote:
> > >
> > > On Mon, Dec 30, 2019 at 1:34 PM Arnd Bergmann <arnd@...db.de> wrote:

> > Returning success from clock_gettime() on a kernel with only
> > time64 support and a libc with only time32 support (or vice
> > versa) would be a bug.
>
> Ah, right, hence why the 32-bit compat code is behind a
> still-on-by-default-but-not-for-long menu option.

I expect this to remain on-by-default for a rather long time, as we still
to run old binaries well into 2030s. Making it configurable is done for
two reasons:

- on embedded systems that have all user space built with time64,
  turning this off can make the kernel slightly smaller

- turning it off lets you check that no code relies on calling the old
  interfaces internally, bypassing the C library, in a way that works
  at the moment but may break after 2038.

         Arnd