linux-kernel - Re: (subset) [PATCH] mfd: lpc_ich: Fix ARRAY_SIZE usage for apl_gpio

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Message-ID: <aBSJz4Nvyzh4c9AO@smile.fi.intel.com>
Date: Fri, 2 May 2025 12:01:03 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Lee Jones <lee@...nel.org>
Cc: Peter Tyser <ptyser@...-inc.com>, Purva Yeshi <purvayeshi550@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: (subset) [PATCH] mfd: lpc_ich: Fix ARRAY_SIZE usage for
 apl_gpio_resources

On Fri, May 02, 2025 at 08:27:32AM +0100, Lee Jones wrote:
> On Fri, 02 May 2025, Andy Shevchenko wrote:
> > Thu, May 01, 2025 at 01:07:25PM +0100, Lee Jones kirjoitti:
> > > On Thu, 24 Apr 2025, Andy Shevchenko wrote:
> > > > On Fri, Apr 04, 2025 at 02:13:08PM +0100, Lee Jones wrote:
> > > > > On Sat, 22 Mar 2025 18:48:41 +0530, Purva Yeshi wrote:

[...]

> > > > > Applied, thanks!
> > > > > 
> > > > > [1/1] mfd: lpc_ich: Fix ARRAY_SIZE usage for apl_gpio_resources
> > > > >       commit: 87e172b0fdd3aa4e3d099884e608dbc70ee3e663
> > > > 
> > > > Can this be reverted ASAP, please? See below why.
> > > > 
> > > > There is no problem with the code. The original author of the change
> > > > haven't proved otherwise.
> > > > 
> > > > The change made it much worse to read and maintain. By the way, it actually
> > > > _added_ the problem as far as I can see with my small test program.
> > > > 
> > > > Let's just calculate based on the sizeof(struct foo) taken as 10 for
> > > > simplicity and array size as 4x2. The full size of the array is
> > > > 4 * 2 * 10 bytes. The size of the entry in outer array will be 2 * 10 bytes.
> > > > Now, what ARRAY2D_SIZE do is (4 * 2 * 10 / 10 / (2 * 10 / 10) == 4, and
> > > > that's WRONG! This will make a out-of-boundary accesses possible.
> > > > 
> > > > If smatch can't parse something, it's problem of smatch. No need to "fix"
> > > > the working and robust code. The original code even allows (in theory) to have
> > > > different amount of resources per entry, however it's quite unlikely to happen.
> > > > But at bare minimum it shows the entry taken along with _its_ ARRAY_SIZE()
> > > > and not something common over the outer array.
> > > 
> > > Done.
> > 
> > I still see it as commit
> > https://web.git.kernel.org/pub/scm/linux/kernel/git/lee/mfd.git/commit/?h=for-mfd-next&id=c6c07f8ea2cbb0dca0e529f9ed16df71276515a4
> 
> -ENOPUSH
> 
> Try again.

Thanks, now it's not there.

-- 
With Best Regards,
Andy Shevchenko