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Message-ID: <CALCETrVPnrXVcapWezAw+AwEpcyTybKUpAO4YqVDk+e1yBUoUw@mail.gmail.com>
Date: Mon, 12 Dec 2016 16:32:03 -0800
From: Andy Lutomirski <luto@...nel.org>
To: David Howells <dhowells@...hat.com>
Cc: Andy Lutomirski <luto@...nel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
USB list <linux-usb@...r.kernel.org>, keyrings@...r.kernel.org,
Eric Biggers <ebiggers3@...il.com>,
linux-crypto@...r.kernel.org,
Herbert Xu <herbert@...dor.apana.org.au>,
Stephan Mueller <smueller@...onox.de>
Subject: Re: [PATCH] keys/encrypted: Fix two crypto-on-the-stack bugs
On Mon, Dec 12, 2016 at 2:28 PM, David Howells <dhowells@...hat.com> wrote:
> Andy Lutomirski <luto@...nel.org> wrote:
>
>> +static const char zero_pad[16] = {0};
>
> Isn't there a global page of zeros or something that we can share? Also, you
> shouldn't explicitly initialise it so that it stays in .bss.
This is a double-edged sword. It seems that omitting the
initialization causes it to go in .bss, which isn't read only. I have
no idea why initializing make a difference at all -- the IMO sensible
behavior would be to put it in .rodata as NOBITS either way.
But I'll use empty_zero_page.
>
>> - sg_set_buf(&sg_out[1], pad, sizeof pad);
>> + sg_set_buf(&sg_out[1], zero_pad, sizeof zero_pad);
>
> Can you put brackets on the sizeof?
Will do for v2.
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