linux-kernel - Re: Touchpad multitouch leaves ghost fingers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAEU-x4k_56w17y0DOKG2TRtegGvzVKS9USAERMa1MtO+3wZivA@mail.gmail.com>
Date: Wed, 24 Sep 2025 00:56:25 +0300
From: Yinon Burgansky <yinonburgansky@...il.com>
To: Benjamin Tissoires <bentiss@...nel.org>
Cc: jikos@...nel.org, linux-input@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: Touchpad multitouch leaves ghost fingers

On Tue, Sep 23, 2025 at 7:30 PM Benjamin Tissoires <bentiss@...nel.org> wrote:
> Got something out with https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/204
> that seems to solve your case on the hid-recorder you provided.

Thank you so much!
The install command didn't work properly for me:
```
$ ./install.sh "*DLL0945*"
$ tree /usr/local/lib/firmware
/usr/local/lib/firmware
└── hid
    └── bpf
        └── 0011-Synaptics__DLL0945.bpf.o
$ reboot
$ sudo tree /sys/fs/bpf
/sys/fs/bpf
0 directories, 0 files
```
I tried to add it manually and it seems to work now :)
```
$ sudo udev-hid-bpf add /sys/bus/hid/devices/0018:06CB:CE26.0005
/usr/local/lib/firmware/hid/bpf/0011-Synaptics__DLL0945.bpf.o
$ sudo tree /sys/fs/bpf
/sys/fs/bpf
└── hid
    └── 0018_06CB_CE26_0005
        └── 0011-Synaptics__DLL0945_bpf
            └── synaptics_dll0945

4 directories, 1 file
```
But I have to do it manually every time.
Not sure what's wrong, maybe the added udev rule:
```
$ cat /etc/udev/rules.d/81-hid-bpf.rules
ACTION!="add|remove|bind", GOTO="hid_bpf_end"
SUBSYSTEM!="hid", GOTO="hid_bpf_end"

# We lookup the hwdb during bind to set the property, but we don't do
anything else
IMPORT{builtin}="hwdb --subsystem=hid --lookup-prefix=hid-bpf:"
#ACTION=="add", ENV{.HID_BPF}=="1",
RUN{program}+="@@BINDIR@@/udev-hid-bpf add $sys$devpath"
#MARKER
ACTION=="add", ENV{.HID_BPF}=="1",
RUN{program}+="/usr/local/bin/udev-hid-bpf add $sys$devpath"
#ACTION=="remove", ENV{.HID_BPF}=="1",
RUN{program}+="@@BINDIR@@/udev-hid-bpf remove $sys$devpath"
#MARKER
ACTION=="remove", ENV{.HID_BPF}=="1",
RUN{program}+="/usr/local/bin/udev-hid-bpf remove $sys$devpath"

LABEL="hid_bpf_end"
```
this is the udevadm info (after reboot, it is sometimes hidraw3
sometimes hidraw4):
```
$  udevadm info --query=all --name=/dev/hidraw4
P: /devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-1/i2c-DLL0945:00/0018:06CB:CE26.0005/hidraw/hidraw4
M: hidraw4
R: 4
J: c242:4
U: hidraw
D: c 242:4
N: hidraw4
L: 0
E: DEVPATH=/devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-1/i2c-DLL0945:00/0018:06CB:CE26.0005/hidraw/hidraw4
E: DEVNAME=/dev/hidraw4
E: MAJOR=242
E: MINOR=4
E: SUBSYSTEM=hidraw
E: USEC_INITIALIZED=3980846
E: ID_VENDOR_FROM_DATABASE=Dell Inc
E: ID_PATH=pci-0000:00:15.1-platform-i2c_designware.1
E: ID_PATH_TAG=pci-0000_00_15_1-platform-i2c_designware_1
E: ID_FOR_SEAT=hidraw-pci-0000_00_15_1-platform-i2c_designware_1
E: TAGS=:seat:
E: CURRENT_TAGS=:seat:
```

Thank you for the quick fix, it seems to work great so far!
Yinon