linux-kernel - Re: [PATCH] HID: pidff: Fix condition effect bit clearing

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Message-ID: <618af8dc-7698-4335-9d0a-fc7ec36cce9f@kernel.org>
Date: Wed, 4 Feb 2026 12:58:47 +0100
From: Jiri Slaby <jirislaby@...nel.org>
To: Tomasz Pakuła <tomasz.pakula.oficjalny@...il.com>,
 jikos@...nel.org, bentiss@...nel.org, sashal@...nel.org
Cc: oleg@...arenk.ooo, linux-input@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] HID: pidff: Fix condition effect bit clearing

On 03. 02. 26, 18:42, Tomasz Pakuła wrote:
> As reported by MPDarkGuy on discord, NULL pointer dereferences were
> happening because not all the conditional effects bits were cleared.
> 
> Properly clear all conditional effect bits from ffbit
> 
> Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@...il.com>
> ---
> 
> Urgent for 6.19 rc period and backports for 6.18
> 
>   drivers/hid/usbhid/hid-pidff.c | 11 +++++++----
>   1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hid/usbhid/hid-pidff.c b/drivers/hid/usbhid/hid-pidff.c
> index a4e700b40ba9..56d6af39ba81 100644
> --- a/drivers/hid/usbhid/hid-pidff.c
> +++ b/drivers/hid/usbhid/hid-pidff.c
> @@ -1452,10 +1452,13 @@ static int pidff_init_fields(struct pidff_device *pidff, struct input_dev *dev)
>   		hid_warn(pidff->hid, "unknown ramp effect layout\n");
>   
>   	if (PIDFF_FIND_FIELDS(set_condition, PID_SET_CONDITION, 1)) {
> -		if (test_and_clear_bit(FF_SPRING, dev->ffbit)   ||
> -		    test_and_clear_bit(FF_DAMPER, dev->ffbit)   ||
> -		    test_and_clear_bit(FF_FRICTION, dev->ffbit) ||
> -		    test_and_clear_bit(FF_INERTIA, dev->ffbit))
> +		bool test = false;
> +
> +		test |= test_and_clear_bit(FF_SPRING, dev->ffbit);
> +		test |= test_and_clear_bit(FF_DAMPER, dev->ffbit);
> +		test |= test_and_clear_bit(FF_FRICTION, dev->ffbit);
> +		test |= test_and_clear_bit(FF_INERTIA, dev->ffbit);

You could use | directly in the if, perhaps with a comment.

> +		if (test)
>   			hid_warn(pidff->hid, "unknown condition effect layout\n");
>   	}
>   

-- 
js
suse labs