[PATCH] HID: pidff: Fix condition effect bit clearing

[PATCH] HID: pidff: Fix condition effect bit clearing

[Tomasz Pakuła]

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@gmail.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);
+		if (test)
 			hid_warn(pidff->hid, "unknown condition effect layout\n");
 	}
 
-- 
2.52.0

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

[Greg KH]

On Tue, Feb 03, 2026 at 06:42:41PM +0100, 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@gmail.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);
> +		if (test)
>  			hid_warn(pidff->hid, "unknown condition effect layout\n");
>  	}
>  
> -- 
> 2.52.0
> 
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

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

[Jiri Slaby]

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@gmail.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

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

[Tomasz Pakuła]

On Wed, 2026-02-04 at 12:58 +0100, Jiri Slaby wrote:
> You could use | directly in the if, perhaps with a comment.
> 

That's actually pretty neat. Didn't think about it. Thanks!

Tomasz