From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, hpa@zytor.com,
samitolvanen@google.com, x86@kernel.org,
linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] x86/kprobes: Prohibit probing on compiler generated CFI checking code
Date: Thu, 27 Jul 2023 09:40:07 +0900 [thread overview]
Message-ID: <20230727094007.96e35433ec7ce10e3010359b@kernel.org> (raw)
In-Reply-To: <20230726092917.GB3802077@hirez.programming.kicks-ass.net>
On Wed, 26 Jul 2023 11:29:17 +0200
Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, Jul 26, 2023 at 12:23:17PM +0900, Masami Hiramatsu wrote:
> > On Tue, 11 Jul 2023 10:50:58 +0900
> > "Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:
> >
> > > From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > >
> > > Prohibit probing on the compiler generated CFI typeid checking code
> > > because it is used for decoding typeid when CFI error happens.
> > >
> > > The compiler generates the following instruction sequence for indirect
> > > call checks on x86;
> > >
> > > movl -<id>, %r10d ; 6 bytes
> > > addl -4(%reg), %r10d ; 4 bytes
> > > je .Ltmp1 ; 2 bytes
> > > ud2 ; <- regs->ip
> > >
> > > And handle_cfi_failure() decodes these instructions (movl and addl)
> > > for the typeid and the target address. Thus if we put a kprobe on
> > > those instructions, the decode will fail and report a wrong typeid
> > > and target address.
> > >
> > >
> >
> > Hi Peter,
> >
> > Can I pick this to probes/fixes branch ?
>
> I'll stick them in tip/x86/core, that ok?
Yes, since it is for CFI change.
Thank you,
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
prev parent reply other threads:[~2023-07-27 0:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-11 1:50 [PATCH v2 0/2] x86: kprobes: Fix CFI_CLANG related issues Masami Hiramatsu (Google)
2023-07-11 1:50 ` [PATCH v2 1/2] kprobes: Prohibit probing on CFI preamble symbol Masami Hiramatsu (Google)
2023-07-28 22:49 ` Steven Rostedt
2023-07-29 12:57 ` Masami Hiramatsu
2023-07-11 1:50 ` [PATCH v2 2/2] x86/kprobes: Prohibit probing on compiler generated CFI checking code Masami Hiramatsu (Google)
2023-07-26 3:23 ` Masami Hiramatsu
2023-07-26 9:29 ` Peter Zijlstra
2023-07-27 0:40 ` Masami Hiramatsu [this message]
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