linux-kernel - Re: [PATCH v2 1/1] gpiolib: acpi: Fix potential out-of-boundary left shift

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Message-ID: <aXjCfwnnASFZ1Ghh@smile.fi.intel.com>
Date: Tue, 27 Jan 2026 15:49:51 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc: Mika Westerberg <westeri@...nel.org>, linux-gpio@...r.kernel.org,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	Linus Walleij <linusw@...nel.org>,
	Bartosz Golaszewski <brgl@...nel.org>
Subject: Re: [PATCH v2 1/1] gpiolib: acpi: Fix potential out-of-boundary left
 shift

On Tue, Jan 27, 2026 at 02:43:00PM +0100, Mika Westerberg wrote:
> On Tue, Jan 27, 2026 at 12:06:30PM +0100, Andy Shevchenko wrote:
> > GPIO Address Space handler gets a pointer to the in or out value.
> > This value is supposed to be at least 64-bit, but it's not limited
> > to be exactly 64-bit. When ACPI tables are being parsed, for
> > the bigger Connection():s ACPICA creates a Buffer instead of regular
> > Integer object. The Buffer exists as long as Namespace holds
> > the certain Connection(). Hence we can access the necessary bits
> > without worrying. On the other hand, the left shift, used in
> > the code, is limited by 31 (on 32-bit platforms) and otherwise
> > considered to be Undefined Behaviour. Also the code uses only
> > the first 64-bit word for the value, and anything bigger than 63
> > will be also subject to UB. Fix all this by modifying the code
> > to correctly set or clear the respective bit in the bitmap constructed
> > of 64-bit words.
> > 
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> 
> Perfect, thanks!

> Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>

Thank you!

Bart, since you picked up the patch in the same lines of code, feel free to
take this one on top (I think it's your gpio/for-current branch).

-- 
With Best Regards,
Andy Shevchenko