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Sat, 25 Jul 2026 01:10:00 -0700 (PDT) Message-ID: <93177ed2-10ca-40a0-9efc-95d83913e59b@gmail.com> Date: Sat, 25 Jul 2026 16:09:47 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: [PATCH v2] Input: tca8418_keypad - fix potential infinite loop and OOB access on invalid keycodes From: Liang Zhan To: dmitry.torokhov@gmail.com Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit The current code checks the raw register value against zero to detect an empty FIFO. However, the TCA8418 datasheet defines key code 0 as the empty-FIFO condition. If the hardware returns garbage data, the loop may never terminate and the extracted keycode can cause an out-of-bounds access on keymap[]. Move the empty-FIFO check to operate on the extracted key code so that the loop terminates correctly. Additionally, validate row/column indices against the configured matrix dimensions before indexing into the keymap array, skipping invalid events. Cc: stable@vger.kernel.org Signed-off-by: Zhian Liang --- changes in v2: - Moved empty-FIFO check to operate on extracted key code instead of raw register value. - Added row/col validation against configured matrix dimensions. - Dropped explicit 0xFF check as requested. --- drivers/input/keyboard/tca8418_keypad.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/input/keyboard/tca8418_keypad.c b/drivers/input/keyboard/tca8418_keypad.c index b124e576feca..36d4a7c38bb1 100644 --- a/drivers/input/keyboard/tca8418_keypad.c +++ b/drivers/input/keyboard/tca8418_keypad.c @@ -114,6 +114,8 @@ struct tca8418_keypad { struct input_dev *input; unsigned int row_shift; + unsigned int rows; + unsigned int cols; }; /* @@ -171,19 +173,28 @@ static void tca8418_read_keypad(struct tca8418_keypad *keypad_data) break; } - /* Assume that key code 0 signifies empty FIFO */ - if (reg <= 0) - break; state = reg & KEY_EVENT_VALUE; code = reg & KEY_EVENT_CODE; + /* Key code 0 signifies empty FIFO */ + if (!code) + break; + row = code / TCA8418_MAX_COLS; col = code % TCA8418_MAX_COLS; row = (col) ? row : row - 1; col = (col) ? col - 1 : TCA8418_MAX_COLS - 1; + /* Validate against configured matrix size */ + if (row >= keypad_data->rows || col >= keypad_data->cols) { + dev_err(&keypad_data->client->dev, + "invalid key code %d (row %d, col %d)\n", + code, row, col); + continue; + } + code = MATRIX_SCAN_CODE(row, col, keypad_data->row_shift); input_event(input, EV_MSC, MSC_SCAN, code); input_report_key(input, keymap[code], state); @@ -298,6 +309,8 @@ static int tca8418_keypad_probe(struct i2c_client *client) keypad_data->client = client; keypad_data->row_shift = row_shift; + keypad_data->rows = rows; + keypad_data->cols = cols; /* Read key lock register, if this fails assume device not present */ error = tca8418_read_byte(keypad_data, REG_KEY_LCK_EC, ®); -- 2.34.1