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([187.13.206.89]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-5c99149d764sm739548e0c.3.2026.09.15.04.14.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Sep 2026 04:14:57 -0700 (PDT) From: Aldo Ariel Panzardo To: Jiri Kosina , Benjamin Tissoires Cc: Ping Cheng , Jason Gerecke , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Aldo Ariel Panzardo Subject: [PATCH] HID: wacom: avoid overflows in sequence number tracking Date: Tue, 15 Sep 2026 08:14:47 -0300 Message-ID: <20260915111448.2726869-1-qwe.aldo@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The dropped-packet calculation derives the sequence range in signed int arithmetic. A sequence field whose logical range spans all signed 32-bit values makes the range calculation wrap to zero, so the following modulo triggers a divide exception. Do the range and delta calculations in s64, and normalize the delta after the modulo. Also avoid overflowing value + 1 when the received value is at the logical maximum. Fixes: 359673ea3a20 ("HID: wacom: Support sequence numbers smaller than 16-bit") Cc: stable@vger.kernel.org Signed-off-by: Aldo Ariel Panzardo --- drivers/hid/wacom_wac.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c index da1f0ea856..39ffe5e7c7 100644 --- a/drivers/hid/wacom_wac.c +++ b/drivers/hid/wacom_wac.c @@ -2530,13 +2530,21 @@ static void wacom_wac_pen_event(struct hid_device *hdev, struct hid_field *field case WACOM_HID_WD_SEQUENCENUMBER: if (wacom_wac->hid_data.sequence_number != value && wacom_wac->hid_data.sequence_number >= 0) { - int sequence_size = field->logical_maximum - field->logical_minimum + 1; - int drop_count = (value - wacom_wac->hid_data.sequence_number) % sequence_size; - hid_warn(hdev, "Dropped %d packets", drop_count); + s64 sequence_size = (s64)field->logical_maximum - + field->logical_minimum + 1; + s64 drop_count = (s64)value - + wacom_wac->hid_data.sequence_number; + + drop_count %= sequence_size; + if (drop_count < 0) + drop_count += sequence_size; + hid_warn(hdev, "Dropped %lld packets", + (long long)drop_count); } - wacom_wac->hid_data.sequence_number = value + 1; - if (wacom_wac->hid_data.sequence_number > field->logical_maximum) + if (value >= field->logical_maximum) wacom_wac->hid_data.sequence_number = field->logical_minimum; + else + wacom_wac->hid_data.sequence_number = value + 1; return; } -- 2.43.0