linux-kernel - Re: System Call trashing registers

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] [day] [month] [year] [list]

Message-ID: <87a5u54tlm.ffs@tglx>
Date:   Fri, 01 Sep 2023 20:49:09 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Joshua Hudson <joshudson@...il.com>,
        Ammar Faizi <ammarfaizi2@...weeb.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        x86-ml <x86@...nel.org>
Subject: Re: System Call trashing registers

On Fri, Sep 01 2023 at 10:38, Joshua Hudson wrote:
> On Fri, Sep 1, 2023 at 9:24 AM Ammar Faizi <ammarfaizi2@...weeb.org> wrote:
>
> Correction: it's been fixed again. Sorry about that.

When exactly was it broken? Which kernel version?

The save/restore mechanism is not changing every other day.

> I know the asmutils tools have been broken for a decade, but they're
> working now.
>
> What would happen is system calls that take arguments in ecx and edx would find
> ecx and edx trashed, but only a few calls actually did this, the
> primary offender
> being open(). The best regression test seems to be hexdump from
> asmutils because the
> corruption would reliably crash the binary. sched_yeild was never an
> affected syscall.

It does absolutely not matter which syscall is used. The save/restore
mechanism is identical for all syscalls.

Thanks,

        tglx