linux-kernel - Re: [PATCH] platform/surface: aggregator: Fix access of unaligned value

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Message-ID: <YCUrb+yAdBCagxvv@smile.fi.intel.com>
Date:   Thu, 11 Feb 2021 15:04:47 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Maximilian Luz <luzmaximilian@...il.com>
Cc:     Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <mgross@...ux.intel.com>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-test-robot <lkp@...el.com>
Subject: Re: [PATCH] platform/surface: aggregator: Fix access of unaligned
 value

On Thu, Feb 11, 2021 at 12:58:48PM +0100, Maximilian Luz wrote:
> On 2/11/21 11:22 AM, Andy Shevchenko wrote:
> > On Thu, Feb 11, 2021 at 12:04:11AM +0100, Maximilian Luz wrote:
> > > The raw message frame length is unaligned and explicitly marked as
> > > little endian. It should not be accessed without the appropriatte
> > > accessor functions. Fix this.

...

> > Also it's possible to annotate temporary variable and use it, but it seems not
> > worth to do.
> 
> Now that you mention it, we already have the correct frame length in
> payload.len. Let me draft up a new patch with that.

Good!

> > Side question: Do you think the below is correct (& operator)?
> > 
> >          sp.len = get_unaligned_le16(&((struct ssh_frame *)sf.ptr)->len);
> > 
> > To me seems like you take an address to len member rather its value.
> 
> That's the point though, no? The signature is
> 
>         u16 get_unaligned_le16(const void *p)
> 
> so we do want a pointer to the len member. So I believe that is correct.

Indeed. I messed up with le16_to_cpu().

-- 
With Best Regards,
Andy Shevchenko