From: "H. Peter Anvin" <hpa@linux.intel.com>
To: Philipp Kern <pkern@google.com>, Andy Lutomirski <luto@amacapital.net>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"H. J. Lu" <hjl.tools@gmail.com>, Eric Paris <eparis@redhat.com>
Subject: Re: [PATCH] x32: Mask away the x32 syscall bit in the ptrace codepath
Date: Wed, 28 May 2014 15:37:17 -0700 [thread overview]
Message-ID: <5386651D.9080001@linux.intel.com> (raw)
In-Reply-To: <CAA2ZrUSzXUp=uipjwCDLsXPOhPwp7m1oSfR8zdKJaQCgg2aoeQ@mail.gmail.com>
On 05/28/2014 02:53 PM, Philipp Kern wrote:
> On Wed, May 28, 2014 at 11:43 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>> However: are you sure that entry_64.S handles this? It looks like
>> tracesys has higher priority than badsys. And strace can certainly
>> see out-of-range syscalls. […]
>
> Not only can it see them: It must see that this bit is set as that's
> the only identifier it has to deduce that the binary is running in x32
> mode.
Yes... keep in mind the ABI is a local property: just because the binary
is running in x32 mode doesn't mean it can't access x86-64 or i386
system calls (or similar for x86-64 processes.) A process started in
i386 mode can transition to long mode and execute x86-64 or x32 system
calls, too.
-hpa
prev parent reply other threads:[~2014-05-28 22:37 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-28 12:19 [PATCH] x32: Mask away the x32 syscall bit in the ptrace codepath Philipp Kern
2014-05-28 20:47 ` Andy Lutomirski
2014-05-28 20:58 ` Philipp Kern
2014-05-28 21:01 ` H. Peter Anvin
2014-05-28 21:15 ` Andy Lutomirski
2014-05-28 21:19 ` H. Peter Anvin
2014-05-28 21:43 ` Andy Lutomirski
2014-05-28 21:53 ` Philipp Kern
2014-05-28 21:55 ` Andy Lutomirski
2014-05-28 22:37 ` H. Peter Anvin [this message]
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