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]
Date:   Wed, 29 Mar 2017 09:45:12 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Jan Kratochvil <jan.kratochvil@...hat.com>,
        Pedro Alves <palves@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: syscall_get_error() && TS_ checks

On Wed, Mar 29, 2017 at 9:33 AM, Oleg Nesterov <oleg@...hat.com> wrote:
>
> Firstly, why do we need the IS_ERR_VALUE() check? This is only used by
> do_signal/handle_signal, we do not care if it returns non-zero as long
> as the value can't be confused with -ERESTART.* codes.

There are system calls that can return "negative" values that aren't errors.

Notably mmap() can return a valid pointer with the high bit set.

So syscall_get_error() should return 0 for not just positive return
values, but for those kinds of negative non-error values.

> And why do we need the TS_ checks?

Those may be bogus.

> So why we can't simply change putreg32() to always sign-extend regs->ax
> regs->orig_ax and just do
>
>         static inline long syscall_get_error(struct task_struct *task,
>                                              struct pt_regs *regs)
>         {
>                 return regs-ax;
>         }

That would be *complete* garbage. Lots of system calls return positive
values that sure as hell aren't errors.

                    Linus

Powered by blists - more mailing lists