[PATCH 2/5] HID: wacom: check the input devices in the legacy irq handlers
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COLD16d
From: Jinmo Yang <hidden>
Date: 2026-09-27 04:11:50
Also in:
lkml, stable
Subsystem:
hid core layer, hid wacom driver, the rest · Maintainers:
Jiri Kosina, Benjamin Tissoires, Ping Cheng, Jason Gerecke, Linus Torvalds
wacom_penpartner_irq(), wacom_pl_irq(), wacom_ptu_irq(),
wacom_dtu_irq(), wacom_dtus_irq() and wacom_graphire_irq() take
pen_input, and the latter two also take pad_input, without checking
either.
As described in "HID: wacom: check the input device in the shared
report helpers", a partial interface leaves one or two of the three
input devices NULL on a fully successful probe, and wacom_wac_irq()
still dispatches to these handlers. Seven locations fault, each
reproduced on linux-next 20260925 (x86_64, KASAN) from one /dev/uhid
device plus a single UHID_INPUT2 write:
wacom_wac.c:137 wacom_penpartner_irq pen_input
wacom_wac.c:227 wacom_pl_irq pen_input
wacom_wac.c:244 wacom_ptu_irq pen_input
wacom_wac.c:303 wacom_dtus_irq pad_input
wacom_wac.c:326 wacom_dtus_irq pen_input
wacom_wac.c:391 wacom_graphire_irq pen_input
wacom_wac.c:444 wacom_graphire_irq pad_input
for example, with vendor 0x056a product 0x0030 (PL) and report id 2:
BUG: KASAN: null-ptr-deref in input_event+0x44/0xb0
Read of size 8 at addr 0000000000000028
wacom_wac_irq+0x2b27/0xb3f0
wacom_raw_event+0x68f/0xb60
__hid_input_report+0x398/0x4d0
uhid_char_write+0xa99/0xfc0
Check each pointer where it is taken. wacom_dtus_irq() and
wacom_graphire_irq() serve both pen and pad reports, so the checks are
placed per branch rather than at function entry: an interface that has
a pad but no pen must keep delivering pad events.
wacom_dtu_irq() gets a check too. Its only dereference is in a
dev_dbg(), so it does not fault with CONFIG_DYNAMIC_DEBUG=n, but it is
unconditional in the source.
Fixes: 2a6cdbdd4cc0 ("HID: wacom: Introduce new 'touch_input' device")
Fixes: 862cf5535c0c ("HID: wacom: Introduce a new WACOM_DEVICETYPE_PAD device_type")
Cc: stable@vger.kernel.org
Signed-off-by: Jinmo Yang <redacted>
---
drivers/hid/wacom_wac.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)
diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 177a1e09fd05..794c2865064a 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c@@ -128,6 +128,9 @@ static int wacom_penpartner_irq(struct wacom_wac *wacom) unsigned char *data = wacom->data; struct input_dev *input = wacom->pen_input; + if (!input) + return 0; + switch (data[0]) { case 1: if (data[5] & 0x80) {
@@ -174,6 +177,9 @@ static int wacom_pl_irq(struct wacom_wac *wacom) struct input_dev *input = wacom->pen_input; int prox, pressure; + if (!input) + return 0; + if (data[0] != WACOM_REPORT_PENABLED) { dev_dbg(input->dev.parent, "%s: received unknown report #%d\n", __func__, data[0]);
@@ -233,6 +239,9 @@ static int wacom_ptu_irq(struct wacom_wac *wacom) unsigned char *data = wacom->data; struct input_dev *input = wacom->pen_input; + if (!input) + return 0; + if (data[0] != WACOM_REPORT_PENABLED) { dev_dbg(input->dev.parent, "%s: received unknown report #%d\n", __func__, data[0]);
@@ -263,6 +272,9 @@ static int wacom_dtu_irq(struct wacom_wac *wacom) struct input_dev *input = wacom->pen_input; int prox = data[1] & 0x20; + if (!input) + return 0; + dev_dbg(input->dev.parent, "%s: received report #%d", __func__, data[0]);
@@ -299,6 +311,8 @@ static int wacom_dtus_irq(struct wacom_wac *wacom) return 0; } else if (data[0] == WACOM_REPORT_DTUSPAD) { input = wacom->pad_input; + if (!input) + return 0; input_report_key(input, BTN_0, (data[1] & 0x01)); input_report_key(input, BTN_1, (data[1] & 0x02)); input_report_key(input, BTN_2, (data[1] & 0x04));
@@ -307,6 +321,9 @@ static int wacom_dtus_irq(struct wacom_wac *wacom) data[1] & 0x0f ? PAD_DEVICE_ID : 0); return 1; } else { + if (!input) + return 0; + prox = data[1] & 0x80; if (prox) { switch ((data[1] >> 3) & 3) {
@@ -363,7 +380,7 @@ static int wacom_graphire_irq(struct wacom_wac *wacom) } prox = data[1] & 0x80; - if (prox || wacom->id[0]) { + if (input && (prox || wacom->id[0])) { if (prox) { switch ((data[1] >> 5) & 3) {
@@ -438,7 +455,7 @@ static int wacom_graphire_irq(struct wacom_wac *wacom) switch (features->type) { case WACOM_G4: prox = data[7] & 0xf8; - if (prox || wacom->id[1]) { + if (pad_input && (prox || wacom->id[1])) { wacom->id[1] = PAD_DEVICE_ID; input_report_key(pad_input, BTN_BACK, (data[7] & 0x40)); input_report_key(pad_input, BTN_FORWARD, (data[7] & 0x80));
@@ -453,7 +470,7 @@ static int wacom_graphire_irq(struct wacom_wac *wacom) case WACOM_MO: prox = (data[7] & 0xf8) || data[8]; - if (prox || wacom->id[1]) { + if (pad_input && (prox || wacom->id[1])) { wacom->id[1] = PAD_DEVICE_ID; input_report_key(pad_input, BTN_BACK, (data[7] & 0x08)); input_report_key(pad_input, BTN_LEFT, (data[7] & 0x20));
@@ -468,7 +485,7 @@ static int wacom_graphire_irq(struct wacom_wac *wacom) break; case GRAPHIRE_BT: prox = data[7] & 0x03; - if (prox || wacom->id[1]) { + if (pad_input && (prox || wacom->id[1])) { wacom->id[1] = PAD_DEVICE_ID; input_report_key(pad_input, BTN_0, (data[7] & 0x02)); input_report_key(pad_input, BTN_1, (data[7] & 0x01));
--
2.53.0