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From: Michael Ellerman <mpe@ellerman.id.au>
To: Kees Cook <keescook@chromium.org>, Thomas Gleixner <tglx@linutronix.de>
Cc: Robert O'Callahan <rocallahan@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"maintainer\:X86 ARCHITECTURE \(32-BIT AND 64-BIT\)"
	<x86@kernel.org>,
	linux-arch@vger.kernel.org, Will Deacon <will@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Mark Rutland <mark.rutland@arm.com>,
	Keno Fischer <keno@juliacomputing.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	kvm list <kvm@vger.kernel.org>,
	Gabriel Krisman Bertazi <krisman@collabora.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Kyle Huey <me@kylehuey.com>
Subject: Re: [REGRESSION] x86/entry: Tracer no longer has opportunity to change the syscall number at entry via orig_ax
Date: Thu, 17 Sep 2020 10:39:40 +1000	[thread overview]
Message-ID: <875z8dp777.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <202009141303.08B39E5783@keescook>

Kees Cook <keescook@chromium.org> writes:
> On Sun, Sep 13, 2020 at 08:27:23PM +0200, Thomas Gleixner wrote:
>> On Sun, Sep 13 2020 at 17:44, Michael Ellerman wrote:
>> > Kees Cook <keescook@chromium.org> writes:
>> > diff --git a/kernel/entry/common.c b/kernel/entry/common.c
>> > index 18683598edbc..901361e2f8ea 100644
>> > --- a/kernel/entry/common.c
>> > +++ b/kernel/entry/common.c
>> > @@ -60,13 +60,15 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
>> >                         return ret;
>> >         }
>> >  
>> > +       syscall = syscall_get_nr(current, regs);
>> > +
>> >         if (unlikely(ti_work & _TIF_SYSCALL_TRACEPOINT))
>> >                 trace_sys_enter(regs, syscall);
>> >  
>> >         syscall_enter_audit(regs, syscall);
>> >  
>> >         /* The above might have changed the syscall number */
>> > -       return ret ? : syscall_get_nr(current, regs);
>> > +       return ret ? : syscall;
>> >  }
>> 
>> Yup, this looks right. Can you please send a proper patch?
>
> I already did on Friday:
> https://lore.kernel.org/lkml/20200912005826.586171-1-keescook@chromium.org/

Thanks.

cheers

      reply	other threads:[~2020-09-17  0:48 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-19 17:14 [REGRESSION] x86/entry: Tracer no longer has opportunity to change the syscall number at entry via orig_ax Kyle Huey
2020-08-19 19:44 ` Thomas Gleixner
2020-08-20 17:26   ` Kyle Huey
2020-08-20 21:09   ` Kees Cook
2020-08-21  0:35     ` Thomas Gleixner
     [not found]   ` <87a6xzrr89.fsf@mpe.ellerman.id.au>
2020-09-11 18:58     ` Kees Cook
2020-09-12  0:10     ` Kees Cook
2020-09-13  7:44       ` Michael Ellerman
2020-09-13 18:27         ` Thomas Gleixner
2020-09-14 20:04           ` Kees Cook
2020-09-17  0:39             ` Michael Ellerman [this message]

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