kernel/linux.git/drivers/hid/hid-multitouch.c, branch v6.12.101

HID: multitouch: fix out-of-bounds bit access on mt_io_flags

2026-07-24T14:11:51+00:00

[ Upstream commit 8813b0612275cc61fe9e6603d0ee019247ade6be ] mt_io_flags is a single unsigned long, but mt_process_slot(), mt_release_pending_palms() and mt_release_contacts() use it as a per-slot bitmap indexed by the slot number. That slot number is only bounded by td->maxcontacts, which is taken from the device's ContactCountMaximum feature report and can be up to 255, not by BITS_PER_LONG. As a result, a multitouch device that advertises a large contact count makes set_bit()/clear_bit() operate past the mt_io_flags word and corrupt the adjacent members of struct mt_device. The sticky-fingers release timer is the easiest way to reach this. mt_release_contacts() runs for (i = 0; i < mt->num_slots; i++) clear_bit(i, &td->mt_io_flags); with num_slots == maxcontacts. For maxcontacts around 250 the loop clears the bits that overlap td->applications.next, zeroing that list head, and the list_for_each_entry() that immediately follows then dereferences NULL. The kernel panics from timer (softirq) context. On a KASAN build this shows up as a general protection fault in mt_release_contacts() with a null-ptr-deref at offset 0x58, which is offsetof(struct mt_application, num_received). The state is reachable from an untrusted USB or Bluetooth HID multitouch device; no local privileges are required. Store the per-slot active state in a separately allocated bitmap sized for maxcontacts, the same pattern already used for pending_palm_slots, and keep only MT_IO_FLAGS_RUNNING in mt_io_flags. The two "mt_io_flags & MT_IO_SLOTS_MASK" arming checks become bitmap_empty(td->active_slots, td->maxcontacts). Move MT_IO_FLAGS_RUNNING back to bit 0. It was bumped to bit 32 by the same commit to leave the low byte for the slot bits; with the slot bits gone it fits in bit 0 again, which also keeps it within the unsigned long on 32-bit. Fixes: 46f781e0d151 ("HID: multitouch: fix sticky fingers") Cc: stable@vger.kernel.org Signed-off-by: Trung Nguyen Signed-off-by: Benjamin Tissoires Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

HID: pass the buffer size to hid_report_raw_event

2026-06-09T10:25:46+00:00

[ Upstream commit 2c85c61d1332e1e16f020d76951baf167dcb6f7a ] commit 0a3fe972a7cb ("HID: core: Mitigate potential OOB by removing bogus memset()") enforced the provided data to be at least the size of the declared buffer in the report descriptor to prevent a buffer overflow. However, we can try to be smarter by providing both the buffer size and the data size, meaning that hid_report_raw_event() can make better decision whether we should plaining reject the buffer (buffer overflow attempt) or if we can safely memset it to 0 and pass it to the rest of the stack. Fixes: 0a3fe972a7cb ("HID: core: Mitigate potential OOB by removing bogus memset()") Cc: stable@vger.kernel.org Signed-off-by: Benjamin Tissoires Acked-by: Johan Hovold Reviewed-by: Greg Kroah-Hartman Signed-off-by: Jiri Kosina Stable-dep-of: 206342541fc8 ("HID: core: introduce hid_safe_input_report()") (cherry picked from commit 509c2605065004fc4cd86ee50a9350d402785307) [Lee: Backported to linux-6.12.y and beyond] Signed-off-by: Lee Jones Signed-off-by: Sasha Levin

HID: multitouch: Check to ensure report responses match the request

2026-04-11T12:24:29+00:00

[ Upstream commit e716edafedad4952fe3a4a273d2e039a84e8681a ] It is possible for a malicious (or clumsy) device to respond to a specific report's feature request using a completely different report ID. This can cause confusion in the HID core resulting in nasty side-effects such as OOB writes. Add a check to ensure that the report ID in the response, matches the one that was requested. If it doesn't, omit reporting the raw event and return early. Signed-off-by: Lee Jones Signed-off-by: Benjamin Tissoires Signed-off-by: Sasha Levin

HID: multitouch: new class MT_CLS_EGALAX_P80H84

2026-03-13T16:20:38+00:00

[ Upstream commit a2e70a89fa58133521b2deae4427d35776bda935 ] Fixes: f9e82295eec1 ("HID: multitouch: add eGalaxTouch P80H84 support") Signed-off-by: Ian Ray Signed-off-by: Jiri Kosina Signed-off-by: Sasha Levin

HID: multitouch: add quirks for Lenovo Yoga Book 9i

2026-03-13T16:20:38+00:00

[ Upstream commit 822bc5b3744b0b2c2c9678aa1d80b2cf04fdfabf ] The Lenovo Yoga Book 9i is a dual-screen laptop, with a single composite USB device providing both touch and tablet interfaces for both screens. All inputs report through a single device, differentiated solely by report numbers. As there is no way for udev to differentiate the inputs based on USB vendor/product ID or interface numbers, custom naming is required to match against for downstream configuration. A firmware bug also results in an erroneous InRange message report being received after the stylus leaves proximity, blocking later touch events. Add required quirks for Gen 8 to Gen 10 models, including a new quirk providing for custom input device naming and dropping erroneous InRange reports. Signed-off-by: Brian Howard Tested-by: Brian Howard Tested-by: Kris Fredrick Reported-by: Andrei Shumailov Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220386 Signed-off-by: Jiri Kosina Stable-dep-of: a2e70a89fa58 ("HID: multitouch: new class MT_CLS_EGALAX_P80H84") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

HID: multitouch: add eGalaxTouch EXC3188 support

2026-03-04T12:21:07+00:00

[ Upstream commit 8e4ac86b2ddd36fe501e20ecfcc080e536df1f48 ] Add support for the for the EXC3188 touchscreen from eGalaxy. Signed-off-by: Thorsten Schmelzer Signed-off-by: Michael Tretter Signed-off-by: Jiri Kosina Signed-off-by: Sasha Levin

HID: multitouch: add MT_QUIRK_STICKY_FINGERS to MT_CLS_VTL

2026-02-11T12:40:20+00:00

[ Upstream commit ff3f234ff1dcd6d626a989151db067a1b7f0f215 ] Some VTL-class touchpads (e.g. TOPS0102:00 35CC:0104) intermittently fail to release a finger contact. A previous slot remains logically active, accompanied by stale BTN_TOOL_DOUBLETAP state, causing gestures to stay latched and resulting in stuck two-finger scrolling and false right-clicks. Apply MT_QUIRK_STICKY_FINGERS to handle the unreleased contact correctly. Link: https://gitlab.freedesktop.org/libinput/libinput/-/issues/1225 Suggested-by: Benjamin Tissoires Tested-by: DaytonCL Signed-off-by: DaytonCL Signed-off-by: Benjamin Tissoires Signed-off-by: Sasha Levin

HID: multitouch: fix name of Stylus input devices

2025-10-23T14:20:37+00:00

[ Upstream commit aa4daea418ee4215dca5c8636090660c545cb233 ] HID_DG_PEN devices should have a suffix of "Stylus", as pointed out by commit c0ee1d571626 ("HID: hid-input: Add suffix also for HID_DG_PEN"). However, on multitouch devices, these suffixes may be overridden. Before that commit, HID_DG_PEN devices would get the "Stylus" suffix, but after that, multitouch would override them to have an "UNKNOWN" suffix. Just add HID_DG_PEN to the list of non-overriden suffixes in multitouch. Before this fix: [ 0.470981] input: ELAN9008:00 04F3:2E14 UNKNOWN as /devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-16/i2c-ELAN9008:00/0018:04F3:2E14.0001/input/input8 ELAN9008:00 04F3:2E14 UNKNOWN After this fix: [ 0.474332] input: ELAN9008:00 04F3:2E14 Stylus as /devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-16/i2c-ELAN9008:00/0018:04F3:2E14.0001/input/input8 ELAN9008:00 04F3:2E14 Stylus Fixes: c0ee1d571626 ("HID: hid-input: Add suffix also for HID_DG_PEN") Signed-off-by: Thadeu Lima de Souza Cascardo Reviewed-by: Mika Westerberg Signed-off-by: Jiri Kosina Signed-off-by: Sasha Levin

HID: multitouch: fix sticky fingers

2025-10-23T14:20:27+00:00

commit 46f781e0d151844589dc2125c8cce3300546f92a upstream. The sticky fingers quirk (MT_QUIRK_STICKY_FINGERS) was only considering the case when slots were not released during the last report. This can be problematic if the firmware forgets to release a finger while others are still present. This was observed on the Synaptics DLL0945 touchpad found on the Dell XPS 9310 and the Dell Inspiron 5406. Fixes: 4f4001bc76fd ("HID: multitouch: fix rare Win 8 cases when the touch up event gets missing") Cc: stable@vger.kernel.org Signed-off-by: Benjamin Tissoires Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman

HID: multitouch: fix slab out-of-bounds access in mt_report_fixup()

2025-09-04T13:31:53+00:00

commit 0379eb8691b9c4477da0277ae0832036ca4410b4 upstream. A malicious HID device can trigger a slab out-of-bounds during mt_report_fixup() by passing in report descriptor smaller than 607 bytes. mt_report_fixup() attempts to patch byte offset 607 of the descriptor with 0x25 by first checking if byte offset 607 is 0x15 however it lacks bounds checks to verify if the descriptor is big enough before conducting this check. Fix this bug by ensuring the descriptor size is at least 608 bytes before accessing it. Below is the KASAN splat after the out of bounds access happens: [ 13.671954] ================================================================== [ 13.672667] BUG: KASAN: slab-out-of-bounds in mt_report_fixup+0x103/0x110 [ 13.673297] Read of size 1 at addr ffff888103df39df by task kworker/0:1/10 [ 13.673297] [ 13.673297] CPU: 0 UID: 0 PID: 10 Comm: kworker/0:1 Not tainted 6.15.0-00005-gec5d573d83f4-dirty #3 [ 13.673297] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/04 [ 13.673297] Call Trace: [ 13.673297] [ 13.673297] dump_stack_lvl+0x5f/0x80 [ 13.673297] print_report+0xd1/0x660 [ 13.673297] kasan_report+0xe5/0x120 [ 13.673297] __asan_report_load1_noabort+0x18/0x20 [ 13.673297] mt_report_fixup+0x103/0x110 [ 13.673297] hid_open_report+0x1ef/0x810 [ 13.673297] mt_probe+0x422/0x960 [ 13.673297] hid_device_probe+0x2e2/0x6f0 [ 13.673297] really_probe+0x1c6/0x6b0 [ 13.673297] __driver_probe_device+0x24f/0x310 [ 13.673297] driver_probe_device+0x4e/0x220 [ 13.673297] __device_attach_driver+0x169/0x320 [ 13.673297] bus_for_each_drv+0x11d/0x1b0 [ 13.673297] __device_attach+0x1b8/0x3e0 [ 13.673297] device_initial_probe+0x12/0x20 [ 13.673297] bus_probe_device+0x13d/0x180 [ 13.673297] device_add+0xe3a/0x1670 [ 13.673297] hid_add_device+0x31d/0xa40 [...] Fixes: c8000deb6836 ("HID: multitouch: Add support for GT7868Q") Cc: stable@vger.kernel.org Signed-off-by: Qasim Ijaz Reviewed-by: Jiri Slaby Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman