From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794231542; b=HSSV/GhdPbeILWs3lZTtR2GNc1F7Y1SiLRz73tV7rbmpgvkf9fy4ApDqNFGWmCVPrtl1 SRbvsbIIEht7oBAAbOR4NX9fVvvQB/4TSkhHSxbbTGicKefv0Y20YAXApjh2+8mrLJ012 88TJMMa2biP9LkenFCbyV+4QZUbwNfrhVWStzsmns7tzjTuqAhIR1n9M+d/UVnKZ/12cz D3Qoq8WRVe48I76XuT1jYJzS6OzMMFzsSUH+OmJ7JwcYmgQ2QJuGtxuDxj3/bCu8XdoHK lIeg0LPAty2bPCjEO9PvN3ljTOBKMclzfLhkZr/cyAvXFP3/80NECeUZ9OP73G+d/yA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794231542; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=ctAGp7a36ZpsTouqfR2ze9VJSRRZ8iArYNlc0XI0q7I=; b=AOAe7Fckp5LrhiuxBD9zcpQtKUSCpLl1BqDOeDk8uSjrBqp8iLpAVO3jD+bO7T+LgC6a nIS1MLTuwnHrrFW2LPBDfDldnVe3RK/Js5r3HL9c5mr5WKowNfel+knthKT3zR+wD0S9s dvQ28pLl5/5XUfQGlgiruB8JeAKJZup7oYiVLVM69s5r3vY3xq+C++IpjUWIYGerANvZc a+DygtxJJ70clzrwwYQ/3RRIaw+4p+WdGcshUmx2KvbHJjqBha+PKZs/VUkZL0omwaa3v FxtV6QWv5jbTVftCi/G5tpOxvaQNEXxH0Pe74+UfylDuct+GLc33GUMnJfsSUEn20LA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=iDdTgd22; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 58D91606A331; Mon, 9 Nov 2026 13:39:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=iDdTgd22 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3D6611F0089F; Mon, 9 Nov 2026 13:38:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794231541; bh=ctAGp7a36ZpsTouqfR2ze9VJSRRZ8iArYNlc0XI0q7I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=iDdTgd22Aj2YbuzsDdRFyjY8AvOZwfrKo72zUM3fygOVdSOW6ZtJelZChaIqjkJ0D QT6t5OhqkmZJ8cYVszEE4LVfG9jjoYgprF9F4CXh01/sGNJtUMD1Q5xdK9v2NwIHaV OmqopvUwV1dc5fzPOsu6F4ne7SwR7tw66cB8PELdsaAX8pJTUK+r6LUgUgtLl5/lxs 4aNgWddV17ZrCcmEJqyy57HHmGtTbE5unVmb68Ci4Nypml1hdojXYPaxTH23Q61pyV ALD2KR4aPAquygp8aRJ+Pa/0+EW+tgYvoL/I8RMhL1+jY8kW64xD1BjhGiOHxeA0gZ 9FCp1ER2b4g9g== From: Lee Jones To: lee@kernel.org, Jiri Kosina , Benjamin Tissoires , Ping Cheng , Peter Hutterer , Dmitry Torokhov , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org, Jiri Kosina Subject: [STABLE v5.15 1/2] HID: wacom: Fix Use-After-Free in wacom_intuos_pad Date: Mon, 9 Nov 2026 13:38:50 +0000 Message-ID: <20261109133854.3026082-2-lee@kernel.org> X-Mailer: git-send-email 2.56.0.506.g506a7eabc5-goog In-Reply-To: <20261109133854.3026082-1-lee@kernel.org> References: <20261109133854.3026082-1-lee@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit [ Upstream commit ef32877368a7013c060ef6bd03a30b6da2fe0c41 ] wacom_intuos_pad() accesses wacom->shared->touch_input locklessly inside the interrupt handler context. If the Touch sibling device is disconnected, wacom_remove_shared_data() clears 'touch_input' outside any lock, creating a Time-of-Check to Time-of-Use (TOCTOU) race condition where a preempted reader in interrupt context dereferences the freed pointer, leading to a Use-After-Free. Resolve this by introducing RCU protection for the touch_input pointer: - Annotate 'touch_input' in wacom_shared struct with __rcu - Wrap all lockless readers in wacom_wac.c with guard(rcu)() and rcu_dereference() using a unified wacom_report_touch_mute() helper - Update writers in wacom_sys.c using rcu_assign_pointer() - Call synchronize_rcu() in wacom_remove_shared_data() to ensure all active RCU readers have finished before the input device is freed Also wrap wacom_set_shared_values() and touch/pen assignments in wacom_add_shared_data() inside the wacom_udev_list_lock to serialize concurrent probe assignments, and verify that 'shared->touch == hdev' before setting touch_input to prevent concurrent sibling probe state desynchronization. Cc: stable@vger.kernel.org Fixes: 961794a00eab ("Input: wacom - add reporting of SW_MUTE_DEVICE events") Signed-off-by: Lee Jones Acked-by: Ping Cheng Tested-by: Ping Cheng Signed-off-by: Jiri Kosina [Lee: Use explicit mutex_lock()/mutex_unlock() in wacom_remove_shared_data() for -std=gnu89 compatibility and adapt to res_wacom] Signed-off-by: Lee Jones --- drivers/hid/wacom_sys.c | 18 +++++++++++++----- drivers/hid/wacom_wac.c | 36 ++++++++++++++++++------------------ drivers/hid/wacom_wac.h | 2 +- 3 files changed, 32 insertions(+), 24 deletions(-) diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c index b6393a806574..149d3546367f 100644 --- a/drivers/hid/wacom_sys.c +++ b/drivers/hid/wacom_sys.c @@ -885,10 +885,16 @@ static void wacom_remove_shared_data(void *res) data = container_of(wacom_wac->shared, struct wacom_hdev_data, shared); - if (wacom_wac->shared->touch == res_wacom->hdev) + mutex_lock(&wacom_udev_list_lock); + if (wacom_wac->shared->touch == res_wacom->hdev) { wacom_wac->shared->touch = NULL; - else if (wacom_wac->shared->pen == res_wacom->hdev) + rcu_assign_pointer(wacom_wac->shared->touch_input, NULL); + } else if (wacom_wac->shared->pen == res_wacom->hdev) { wacom_wac->shared->pen = NULL; + } + mutex_unlock(&wacom_udev_list_lock); + + synchronize_rcu(); if (kref_put_mutex(&data->kref, wacom_release_shared_data, &wacom_udev_list_lock)) mutex_unlock(&wacom_udev_list_lock); @@ -2350,9 +2356,11 @@ static void wacom_set_shared_values(struct wacom_wac *wacom_wac) } if (wacom_wac->features.device_type & WACOM_DEVICETYPE_TOUCH) { - wacom_wac->shared->type = wacom_wac->features.type; - wacom_wac->shared->touch_input = wacom_wac->touch_input; - wacom_wac->shared->touch = wacom->hdev; + if (wacom_wac->shared->touch == wacom->hdev || !wacom_wac->shared->touch) { + wacom_wac->shared->type = wacom_wac->features.type; + wacom_wac->shared->touch = wacom->hdev; + rcu_assign_pointer(wacom_wac->shared->touch_input, wacom_wac->touch_input); + } } else if (wacom_wac->features.device_type & WACOM_DEVICETYPE_PEN) { /* Pairs with smp_load_acquire() in wacom_sibling_pending() */ smp_store_release(&wacom_wac->shared->pen, wacom->hdev); diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c index 78d7fda68f20..6549439f3203 100644 --- a/drivers/hid/wacom_wac.c +++ b/drivers/hid/wacom_wac.c @@ -510,6 +510,18 @@ static void wacom_intuos_schedule_prox_event(struct wacom_wac *wacom_wac) } } +static void wacom_report_touch_mute(struct wacom_wac *wacom_wac, bool mute) +{ + struct input_dev *touch_input; + + guard(rcu)(); + touch_input = rcu_dereference(wacom_wac->shared->touch_input); + if (touch_input) { + input_report_switch(touch_input, SW_MUTE_DEVICE, mute); + input_sync(touch_input); + } +} + static int wacom_intuos_pad(struct wacom_wac *wacom) { struct wacom_features *features = &wacom->features; @@ -650,12 +662,8 @@ static int wacom_intuos_pad(struct wacom_wac *wacom) input_report_key(input, KEY_CONTROLPANEL, menu); input_report_key(input, KEY_INFO, info); - if (wacom->shared && wacom->shared->touch_input) { - input_report_switch(wacom->shared->touch_input, - SW_MUTE_DEVICE, - !wacom->shared->is_touch_on); - input_sync(wacom->shared->touch_input); - } + if (wacom->shared) + wacom_report_touch_mute(wacom, !wacom->shared->is_touch_on); input_report_abs(input, ABS_RX, strip1); input_report_abs(input, ABS_RY, strip2); @@ -2192,7 +2200,7 @@ static void wacom_wac_pad_event(struct hid_device *hdev, struct hid_field *field */ if ((equivalent_usage == WACOM_HID_WD_MUTE_DEVICE) || (equivalent_usage == WACOM_HID_WD_TOUCHONOFF)) { - if (wacom_wac->shared->touch_input) { + if (wacom_wac->shared) { bool *is_touch_on = &wacom_wac->shared->is_touch_on; if (equivalent_usage == WACOM_HID_WD_MUTE_DEVICE && value) @@ -2200,9 +2208,7 @@ static void wacom_wac_pad_event(struct hid_device *hdev, struct hid_field *field else if (equivalent_usage == WACOM_HID_WD_TOUCHONOFF) *is_touch_on = value; - input_report_switch(wacom_wac->shared->touch_input, - SW_MUTE_DEVICE, !(*is_touch_on)); - input_sync(wacom_wac->shared->touch_input); + wacom_report_touch_mute(wacom_wac, !(*is_touch_on)); } return; } @@ -3324,11 +3330,8 @@ static int wacom_wireless_irq(struct wacom_wac *wacom, size_t len) if ((wacom->shared->type == INTUOSHT || wacom->shared->type == INTUOSHT2) && - wacom->shared->touch_input && wacom->shared->touch_max) { - input_report_switch(wacom->shared->touch_input, - SW_MUTE_DEVICE, data[5] & 0x40); - input_sync(wacom->shared->touch_input); + wacom_report_touch_mute(wacom, data[5] & 0x40); } pid = get_unaligned_be16(&data[6]); @@ -3363,11 +3366,8 @@ static int wacom_status_irq(struct wacom_wac *wacom_wac, size_t len) if ((features->type == INTUOSHT || features->type == INTUOSHT2) && - wacom_wac->shared->touch_input && features->touch_max) { - input_report_switch(wacom_wac->shared->touch_input, - SW_MUTE_DEVICE, data[8] & 0x40); - input_sync(wacom_wac->shared->touch_input); + wacom_report_touch_mute(wacom_wac, data[8] & 0x40); } if (data[9] & 0x02) { /* wireless module is attached */ diff --git a/drivers/hid/wacom_wac.h b/drivers/hid/wacom_wac.h index 0491b19430cd..4f9ef7b21de3 100644 --- a/drivers/hid/wacom_wac.h +++ b/drivers/hid/wacom_wac.h @@ -286,7 +286,7 @@ struct wacom_shared { /* for wireless device to access USB interfaces */ unsigned touch_max; int type; - struct input_dev *touch_input; + struct input_dev __rcu *touch_input; struct hid_device *pen; struct hid_device *touch; bool has_mute_touch_switch; -- 2.56.0.506.g506a7eabc5-goog