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

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Message-ID: <CAMRc=Me=TFk6XZtLJ9XGBdYtQRb=-tLqXy+x7mteBe8ANvqEKA@mail.gmail.com>
Date: Wed, 28 Jan 2026 01:02:11 -0800
From: Bartosz Golaszewski <brgl@...nel.org>
To: Andy Shevchenko <andriy.shevchenko@...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>, 
	Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: Re: [PATCH v2 1/1] gpiolib: acpi: Fix potential out-of-boundary left shift

On Tue, 27 Jan 2026 14:49:51 +0100, Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> said:
> 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).
>

Don't you want a Fixes: and Cc: stable tags?

Bart