linux-kernel - Re: [PATCH v2] rtw_security: fix cast to restricted _

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Message-ID: <CAKgboZ8QUQpiinL0xCxUmcp6nEVU20jXkDXbrK_QisUMiLEo1A@mail.gmail.com>
Date:   Mon, 14 Jun 2021 00:40:27 +0800
From:   Jhih Ming Huang <fbihjmeric@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     fabioaiuto83@...il.com, ross.schm.dev@...il.com,
        maqianga@...ontech.com, marcocesati@...il.com,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] rtw_security: fix cast to restricted __le32

On Sun, Jun 13, 2021 at 8:34 PM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Sun, Jun 13, 2021 at 08:28:58PM +0800, Jhih-Ming Huang wrote:
> > This patch fixes the sparse warning of fix cast to restricted __le32.
> >
> > Last month, there was a change for replacing private CRC-32 routines with
> > in-kernel ones.
> > In that patch, we replaced getcrc32 with crc32_le in calling le32_to_cpu.
> > le32_to_cpu accepts __le32 type as arg, but crc32_le returns unsigned int.
> > That how it introduced the sparse warning.
>
> As crc32_le returns a u32 which is in native-endian format, how can you
> cast it to le32?  Why do you cast it to le32?  Isn't that going to be
> incorrect for big endian systems?
>
> thanks,
>
> greg k-h

Thanks for the fast reply.
Yes, you are right. I did not notice that le32_to_cpu already handles
both of the cases.

So it seems the warning from sparse is false positives, am I right?

thanks

--jmhuang