On Tue, Dec 10, 2024 at 10:36 PM Sasha Levin sashal@kernel.org wrote:

This is a note to let you know that I've just added the patch titled

HID: bpf: Fix NKRO on Mistel MD770

to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: hid-bpf-fix-nkro-on-mistel-md770.patch and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

Please drop this patch (and in all previous releases).

Again, it makes no sense to backport any files in drivers/hid/bpf/progs on kernels before 6.11, and even then, it makes very little value as they are also tracked in a different userspace project (udev-hid-bpf).

FWIW, HID-BPF was introduced in v6.3, so it's even more surprisingly surprising to see such a patch added here.

Cheers, Benjamin

commit cd9ab7edb94431f02c68383c089dc12fbbe00475 Author: Benjamin Tissoires bentiss@kernel.org Date: Thu Oct 17 18:34:58 2024 +0200

HID: bpf: Fix NKRO on Mistel MD770

[ Upstream commit 9bc089307e8dff7797233308372b4a90ce8f79be ]

Mistel MD770 keyboard (using Holtek Semiconductor, Inc. controller) has
a quirk in report descriptor in one of its interfaces (more detail in
the source file). Fix up the descriptor to allow NKRO to work again.

Tested by loading the BPF program and confirming that 8 simultaneous
keypresses work.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=218495
Link: https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/122
Signed-off-by: Tatsuyuki Ishi <ishitatsuyuki@gmail.com>
Acked-by: Jiri Kosina <jkosina@suse.com>
Link: https://patch.msgid.link/20241017-import_bpf_6-13-v2-1-6a7acb89a97f@kernel.org
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/hid/bpf/progs/Mistel__MD770.bpf.c b/drivers/hid/bpf/progs/Mistel__MD770.bpf.c new file mode 100644 index 0000000000000..fb8b5a6968b12 --- /dev/null +++ b/drivers/hid/bpf/progs/Mistel__MD770.bpf.c @@ -0,0 +1,154 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2024 Tatsuyuki Ishi

• */

+#include "vmlinux.h" +#include "hid_bpf.h" +#include "hid_bpf_helpers.h" +#include <bpf/bpf_tracing.h>

+#define VID_HOLTEK 0x04D9 +#define PID_MD770 0x0339 +#define RDESC_SIZE 203

+HID_BPF_CONFIG(

•   HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_HOLTEK, PID_MD770)
  

+);

+/*

• • The Mistel MD770 keyboard reports the first 6 simultaneous key presses
• • through the first interface, and anything beyond that through a second
• • interface. Unfortunately, the second interface's report descriptor has an
• • error, causing events to be malformed and ignored. This HID-BPF driver
• • fixes the descriptor to allow NKRO to work again.
• • For reference, this is the original report descriptor:
• • 0x05, 0x01, // Usage Page (Generic Desktop) 0
• • 0x09, 0x80, // Usage (System Control) 2
• • 0xa1, 0x01, // Collection (Application) 4
• • 0x85, 0x01, // Report ID (1) 6
• • 0x19, 0x81, // Usage Minimum (129) 8
• • 0x29, 0x83, // Usage Maximum (131) 10
• • 0x15, 0x00, // Logical Minimum (0) 12
• • 0x25, 0x01, // Logical Maximum (1) 14
• • 0x95, 0x03, // Report Count (3) 16
• • 0x75, 0x01, // Report Size (1) 18
• • 0x81, 0x02, // Input (Data,Var,Abs) 20
• • 0x95, 0x01, // Report Count (1) 22
• • 0x75, 0x05, // Report Size (5) 24
• • 0x81, 0x01, // Input (Cnst,Arr,Abs) 26
• • 0xc0, // End Collection 28
• • 0x05, 0x0c, // Usage Page (Consumer Devices) 29
• • 0x09, 0x01, // Usage (Consumer Control) 31
• • 0xa1, 0x01, // Collection (Application) 33
• • 0x85, 0x02, // Report ID (2) 35
• • 0x15, 0x00, // Logical Minimum (0) 37
• • 0x25, 0x01, // Logical Maximum (1) 39
• • 0x95, 0x12, // Report Count (18) 41
• • 0x75, 0x01, // Report Size (1) 43
• • 0x0a, 0x83, 0x01, // Usage (AL Consumer Control Config) 45
• • 0x0a, 0x8a, 0x01, // Usage (AL Email Reader) 48
• • 0x0a, 0x92, 0x01, // Usage (AL Calculator) 51
• • 0x0a, 0x94, 0x01, // Usage (AL Local Machine Browser) 54
• • 0x09, 0xcd, // Usage (Play/Pause) 57
• • 0x09, 0xb7, // Usage (Stop) 59
• • 0x09, 0xb6, // Usage (Scan Previous Track) 61
• • 0x09, 0xb5, // Usage (Scan Next Track) 63
• • 0x09, 0xe2, // Usage (Mute) 65
• • 0x09, 0xea, // Usage (Volume Down) 67
• • 0x09, 0xe9, // Usage (Volume Up) 69
• • 0x0a, 0x21, 0x02, // Usage (AC Search) 71
• • 0x0a, 0x23, 0x02, // Usage (AC Home) 74
• • 0x0a, 0x24, 0x02, // Usage (AC Back) 77
• • 0x0a, 0x25, 0x02, // Usage (AC Forward) 80
• • 0x0a, 0x26, 0x02, // Usage (AC Stop) 83
• • 0x0a, 0x27, 0x02, // Usage (AC Refresh) 86
• • 0x0a, 0x2a, 0x02, // Usage (AC Bookmarks) 89
• • 0x81, 0x02, // Input (Data,Var,Abs) 92
• • 0x95, 0x01, // Report Count (1) 94
• • 0x75, 0x0e, // Report Size (14) 96
• • 0x81, 0x01, // Input (Cnst,Arr,Abs) 98
• • 0xc0, // End Collection 100
• • 0x05, 0x01, // Usage Page (Generic Desktop) 101
• • 0x09, 0x02, // Usage (Mouse) 103
• • 0xa1, 0x01, // Collection (Application) 105
• • 0x09, 0x01, // Usage (Pointer) 107
• • 0xa1, 0x00, // Collection (Physical) 109
• • 0x85, 0x03, // Report ID (3) 111
• • 0x05, 0x09, // Usage Page (Button) 113
• • 0x19, 0x01, // Usage Minimum (1) 115
• • 0x29, 0x08, // Usage Maximum (8) 117
• • 0x15, 0x00, // Logical Minimum (0) 119
• • 0x25, 0x01, // Logical Maximum (1) 121
• • 0x75, 0x01, // Report Size (1) 123
• • 0x95, 0x08, // Report Count (8) 125
• • 0x81, 0x02, // Input (Data,Var,Abs) 127
• • 0x05, 0x01, // Usage Page (Generic Desktop) 129
• • 0x09, 0x30, // Usage (X) 131
• • 0x09, 0x31, // Usage (Y) 133
• • 0x16, 0x01, 0x80, // Logical Minimum (-32767) 135
• • 0x26, 0xff, 0x7f, // Logical Maximum (32767) 138
• • 0x75, 0x10, // Report Size (16) 141
• • 0x95, 0x02, // Report Count (2) 143
• • 0x81, 0x06, // Input (Data,Var,Rel) 145
• • 0x09, 0x38, // Usage (Wheel) 147
• • 0x15, 0x81, // Logical Minimum (-127) 149
• • 0x25, 0x7f, // Logical Maximum (127) 151
• • 0x75, 0x08, // Report Size (8) 153
• • 0x95, 0x01, // Report Count (1) 155
• • 0x81, 0x06, // Input (Data,Var,Rel) 157
• • 0x05, 0x0c, // Usage Page (Consumer Devices) 159
• • 0x0a, 0x38, 0x02, // Usage (AC Pan) 161
• • 0x95, 0x01, // Report Count (1) 164
• • 0x81, 0x06, // Input (Data,Var,Rel) 166
• • 0xc0, // End Collection 168
• • 0xc0, // End Collection 169
• • 0x05, 0x01, // Usage Page (Generic Desktop) 170
• • 0x09, 0x06, // Usage (Keyboard) 172
• • 0xa1, 0x01, // Collection (Application) 174
• • 0x85, 0x04, // Report ID (4) 176
• • 0x05, 0x07, // Usage Page (Keyboard) 178
• • 0x95, 0x01, // Report Count (1) 180
• • 0x75, 0x08, // Report Size (8) 182
• • 0x81, 0x03, // Input (Cnst,Var,Abs) 184
• • 0x95, 0xe8, // Report Count (232) 186
• • 0x75, 0x01, // Report Size (1) 188
• • 0x15, 0x00, // Logical Minimum (0) 190
• • 0x25, 0x01, // Logical Maximum (1) 192
• • 0x05, 0x07, // Usage Page (Keyboard) 194
• • 0x19, 0x00, // Usage Minimum (0) 196
• • 0x29, 0xe7, // Usage Maximum (231) 198
• • 0x81, 0x00, // Input (Data,Arr,Abs) 200 <- change to 0x81, 0x02 (Data,Var,Abs)
• • 0xc0, // End Collection 202
• */

+SEC(HID_BPF_RDESC_FIXUP) +int BPF_PROG(hid_rdesc_fixup_mistel_md770, struct hid_bpf_ctx *hctx) +{

•   __u8 *data = hid_bpf_get_data(hctx, 0, HID_MAX_DESCRIPTOR_SIZE);
  

•   if (!data)
  

•           return 0; /* EPERM check */
  

•   if (data[201] == 0x00)
  

•           data[201] = 0x02;
  

•   return 0;
  

+}

+HID_BPF_OPS(mistel_md770) = {

•   .hid_rdesc_fixup = (void *)hid_rdesc_fixup_mistel_md770,
  

+};

+SEC("syscall") +int probe(struct hid_bpf_probe_args *ctx) +{

•   ctx->retval = ctx->rdesc_size != RDESC_SIZE;
  

•   if (ctx->retval)
  

•           ctx->retval = -EINVAL;
  

•   return 0;
  

+}

+char _license[] SEC("license") = "GPL";