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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id i9sm11461663pfq.53.2020.09.14.13.04.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Sep 2020 13:04:08 -0700 (PDT) Date: Mon, 14 Sep 2020 13:04:06 -0700 From: Kees Cook To: Thomas Gleixner Cc: Michael Ellerman , Robert O'Callahan , LKML , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , linux-arch@vger.kernel.org, Will Deacon , Arnd Bergmann , Mark Rutland , Keno Fischer , Paolo Bonzini , kvm list , Gabriel Krisman Bertazi , Sean Christopherson , Kyle Huey Subject: Re: [REGRESSION] x86/entry: Tracer no longer has opportunity to change the syscall number at entry via orig_ax Message-ID: <202009141303.08B39E5783@keescook> References: <87blj6ifo8.fsf@nanos.tec.linutronix.de> <87a6xzrr89.fsf@mpe.ellerman.id.au> <202009111609.61E7875B3@keescook> <87d02qqfxy.fsf@mpe.ellerman.id.au> <87o8m98rck.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87o8m98rck.fsf@nanos.tec.linutronix.de> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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 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/ -- Kees Cook