linux-kernel - Re: [PATCH v3 3/6] crypto: Add Qcom prng driver

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180704061035.GY22377@vkoul-mobl>
Date:   Wed, 4 Jul 2018 11:40:35 +0530
From:   Vinod <vkoul@...nel.org>
To:     Stephan Mueller <smueller@...onox.de>
Cc:     linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Matt Mackall <mpm@...enic.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm@...r.kernel.org, Stephen Boyd <swboyd@...omium.org>,
        Timur Tabi <timur@...eaurora.org>
Subject: Re: [PATCH v3 3/6] crypto: Add Qcom prng driver

On 04-07-18, 09:40, Vinod wrote:
> Hi Stephan,
> 
> On 03-07-18, 15:28, Stephan Mueller wrote:
> > Am Dienstag, 3. Juli 2018, 08:04:31 CEST schrieb Vinod Koul:
> > > +static int qcom_rng_read(struct qcom_rng *rng, void *data, size_t max)
> > > +{
> > > +	size_t currsize = 0;
> > > +	u32 *retdata = data;
> > 
> > How can you be sure that this cast is appropriate? I.e. how is it guaranteed 
> > that data is 4-byte aligned?
> 
> While reading we check the alignment:
> 
>                /* make sure we stay on 32bit boundary */
>                if ((max - currsize) < WORD_SZ)
>                        break;
> 
> > Also, the data variable in qcom_rng_generate is a u8 -- shouldn't this type be 
> > used instead of a void?
> 
> That does make sense to me. IIRC the read is for a byte. I will check
> this and update it

Okay so I rechecked this, the hardware gives 32 bits of random data. I
am thinking of splitting the word and updating by each byte. That way
trailing zero can also be avoided which is the case now

-- 
~Vinod