From: "H. Peter Anvin" <hpa@zytor.com>
To: Richard Henderson <rth@redhat.com>
Cc: "H.J. Lu" <hjl.tools@gmail.com>,
Bernd Schmidt <bernds@codesourcery.com>,
gcc-patches@gcc.gnu.org,
Eric Botcazou <ebotcazou@adacore.com>
Subject: Re: [x32] PATCH: Remove ix86_promote_function_mode
Date: Tue, 21 Jun 2011 01:15:00 -0000 [thread overview]
Message-ID: <0ac1c397-c436-40c5-98dd-4247dcd28311@email.android.com> (raw)
In-Reply-To: <4DFFE3BF.9080605@redhat.com>
Richard Henderson <rth@redhat.com> wrote:
>On 06/20/2011 04:39 PM, H. Peter Anvin wrote:
>> sys_foo:
>> cmpl $10, %edi
>> jae .L1
>>
>> movq foo_table(,%rdi,3), %rax
>> retq
>> .L1:
>> movq $-EINVAL, %rax
>> retq
>>
>> Enter this function with a non-normalized %rdi and you have a
>security
>> hole even though the C is perfectly fine.
>
>Yes, I get that. Isn't it already the case that x86_64 defines the
>upper half of 32-bit inputs as garbage? Assuming you're never
>intending
>to run an x32 kernel, but always an x32 environment within an x86_64
>kernel, where does the talk of security holes wrt non-pointers come
>from?
>
>
>r~
H.J. was proposing an ABI change. I wanted to explain that the current ABI is the way it is for a reason. x32 pointers, however, can and should be zero-extended since they will be 64 bits in the kernel, as you correctly point out.
--
Sent from my mobile phone. Please excuse my brevity and lack of formatting.
prev parent reply other threads:[~2011-06-21 1:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-20 13:55 H.J. Lu
2011-06-20 13:57 ` Bernd Schmidt
2011-06-20 14:13 ` H.J. Lu
2011-06-20 14:41 ` H. Peter Anvin
2011-06-20 14:44 ` Jeff Law
2011-06-20 15:11 ` H.J. Lu
2011-06-20 14:46 ` H.J. Lu
2011-06-20 15:28 ` H. Peter Anvin
2011-06-20 22:58 ` Richard Henderson
2011-06-21 0:33 ` H. Peter Anvin
2011-06-21 0:34 ` Richard Henderson
2011-06-21 1:15 ` H. Peter Anvin [this message]
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