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=1793799829; b=DgkLQvwxLC/4Qon7uGDXi+uxg8basu9Ir+yaUjZNKOzhUIBxhXs8VWWJKMsF29yu8v21 xAbaEm6UwqHz8UakmC1qwpGUaWgdcyi0rNEJC6yL703iVhzMyTOPc/swE6AO6zgCpjhHL 1ZFOk4/sPMPrtpiOC6n1WELNMobgHx8+oRiBNFmA/hnVFYeYBjKT41Ta/rFMJHskWB3JR qIx0ZhJ0QCkFglg4WpNUG4BS4Nf4X4QSDhd6HbtYyN7fc+hdHH9Qf/kC/JexCHJX/d3Xv iKAirO8hqDiEcHxiKDsI84b8+wIHhwNd9Q2r9Y4zPnj0amvgrMgZUUBqytgqLDNsRdA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793799829; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=i8icQTFTRG/1ixiqdj915PPUIVjAmAQVRklVikeo6tI=; b=lKNNT/LOoV/8SkTCtADWkEqtRmTkYqcAj2fj2S+Of3/8hwgxguMW3pbn2kPdeEZrNdIO me9AvoOiZSHwqfnxfAOTaKgPm73L/J1IKuRzs5LZaiaNWWdhIaGK6gSmzZGgsHNKLLtjA TGJMsOcTdotk7P993FIjFPBb1C8+yfj3eglYTCYUO8QehsW84W7k76053NX2khgUv2R0o LP0Ps1Uc7M8jm9YJ6FwehjE9FV+pOwQUvDI3TbIuDXaGUvf1pAJhsOxrgmdAGbljr24/o tgB2D30xrLF6NRxiAXnkgMxnK8O5UAf8tj5D2wzvWhEMEfuW+rEbn4Ju5dwgBwIy3tw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=gbFEVL4V; 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 DA32B606A328 for ; Wed, 4 Nov 2026 13:43:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=gbFEVL4V Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E71A1F00919; Wed, 4 Nov 2026 13:43:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793799828; bh=i8icQTFTRG/1ixiqdj915PPUIVjAmAQVRklVikeo6tI=; h=Subject:To:Cc:From:Date; b=gbFEVL4VvAtdpW514rs5J5CpHWpEGN8dfmyx+DrnnS6r7goliyCwckTQdAOqHgePM abTt/y0Zh7Otaf9UYK0utBtrm5Pq6ODaFk3HHeM0YigCnq+JWrzZXIQsx7PBEOWvKU kGHlvcxwgmAwWF5CgWfAAR6NSRPM4mclrZSPpjQw= Subject: FAILED: patch "[PATCH] HID: wacom: Fix Use-After-Free in wacom_intuos_pad" failed to apply to 5.10-stable tree To: lee@kernel.org,jkosina@suse.com,ping.cheng@wacom.com Cc: From: Date: Wed, 04 Nov 2026 14:43:39 +0100 Message-ID: <2026110439-ramble-ebook-0594@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x ef32877368a7013c060ef6bd03a30b6da2fe0c41 # git commit -s git send-email --to '' --in-reply-to '2026110439-ramble-ebook-0594@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From ef32877368a7013c060ef6bd03a30b6da2fe0c41 Mon Sep 17 00:00:00 2001 From: Lee Jones Date: Wed, 9 Sep 2026 11:12:25 +0000 Subject: [PATCH] HID: wacom: Fix Use-After-Free in wacom_intuos_pad 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 diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c index 4eed2c189017..10f7de515ea2 100644 --- a/drivers/hid/wacom_sys.c +++ b/drivers/hid/wacom_sys.c @@ -875,10 +875,16 @@ static void wacom_remove_shared_data(void *res) data = container_of(wacom_wac->shared, struct wacom_hdev_data, shared); - if (wacom_wac->shared->touch == wacom->hdev) - wacom_wac->shared->touch = NULL; - else if (wacom_wac->shared->pen == wacom->hdev) - wacom_wac->shared->pen = NULL; + scoped_guard(mutex, &wacom_udev_list_lock) { + if (wacom_wac->shared->touch == wacom->hdev) { + wacom_wac->shared->touch = NULL; + rcu_assign_pointer(wacom_wac->shared->touch_input, NULL); + } else if (wacom_wac->shared->pen == wacom->hdev) { + wacom_wac->shared->pen = NULL; + } + } + + synchronize_rcu(); kref_put(&data->kref, wacom_release_shared_data); wacom_wac->shared = NULL; @@ -915,6 +921,7 @@ static int wacom_add_shared_data(struct hid_device *hdev) mutex_unlock(&wacom_udev_list_lock); retval = devm_add_action_or_reset(&hdev->dev, wacom_remove_shared_data, wacom); + return retval; } @@ -2354,9 +2361,11 @@ 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 30df866feac8..c5227530f291 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); @@ -2168,7 +2176,7 @@ 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) @@ -2176,9 +2184,7 @@ 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; } @@ -3396,11 +3402,8 @@ 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]); @@ -3435,11 +3438,8 @@ 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 126bec6e5c0c..a8bbba4a6f37 100644 --- a/drivers/hid/wacom_wac.h +++ b/drivers/hid/wacom_wac.h @@ -285,7 +285,7 @@ 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;