The Elan I2C touchpad driver queries the device for its physical dimensions and trace counts to calculate the device resolution and width. However, if the device firmware or device tree provides invalid zero values for x_traces or y_traces, it results in a fatal division-by-zero exception leading to a kernel panic during device probe. Add checks to ensure these parameters are non-zero before performing the division. If invalid trace values are detected, fall back to a safe default of 1. Additionally, prevent an arithmetic underflow in the touch reporting logic. Previously, if the calculated or fallback width was smaller than ETP_FWIDTH_REDUCE (90), the subtraction would underflow, resulting in a massive unsigned integer being reported to userspace. Clamp the adjusted width to a minimum of 0 to safely handle small physical dimensions and fallback scenarios. Completing the probe with safe fallback values ensures the sysfs nodes are created, keeping the firmware update path intact so a recovery firmware can be flashed to the device.
Showing the changes to drivers/input (1 of 1 file). Show all
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| @@ -428,8 +428,17 @@ static int elan_query_device_parameters(struct elan_tp_data *data) · 427 unmodified lines | ||
| 428 | 428 | if (error) |
| 429 | 429 | return error; |
| 430 | 430 | } |
| 431 | − data->width_x = data->max_x / x_traces; | |
| 432 | − data->width_y = data->max_y / y_traces; | |
| 431 | + | |
| 432 | + if (!x_traces || !y_traces) { | |
| 433 | + dev_warn(&client->dev, | |
| 434 | + "invalid trace numbers: x=%u, y=%u\n", | |
| 435 | + x_traces, y_traces); | |
| 436 | + data->width_x = 1; | |
| 437 | + data->width_y = 1; | |
| 438 | + } else { | |
| 439 | + data->width_x = data->max_x / x_traces; | |
| 440 | + data->width_y = data->max_y / y_traces; | |
| 441 | + } | |
| 433 | 442 | |
| 434 | 443 | if (device_property_read_u32(&client->dev, |
| 435 | 444 | "touchscreen-x-mm", &x_mm) || |
| @@ -443,8 +452,16 @@ static int elan_query_device_parameters(struct elan_tp_data *data) · 7 unmodified lines | ||
| 443 | 452 | data->x_res = elan_convert_resolution(hw_x_res, data->pattern); |
| 444 | 453 | data->y_res = elan_convert_resolution(hw_y_res, data->pattern); |
| 445 | 454 | } else { |
| 446 | − data->x_res = (data->max_x + 1) / x_mm; | |
| 447 | − data->y_res = (data->max_y + 1) / y_mm; | |
| 455 | + if (unlikely(x_mm == 0 || y_mm == 0)) { | |
| 456 | + dev_warn(&client->dev, | |
| 457 | + "invalid physical dimensions: x_mm=%u, y_mm=%u\n", | |
| 458 | + x_mm, y_mm); | |
| 459 | + data->x_res = 1; | |
| 460 | + data->y_res = 1; | |
| 461 | + } else { | |
| 462 | + data->x_res = (data->max_x + 1) / x_mm; | |
| 463 | + data->y_res = (data->max_y + 1) / y_mm; | |
| 464 | + } | |
| 448 | 465 | } |
| 449 | 466 | |
| 450 | 467 | if (device_property_read_bool(&client->dev, "elan,clickpad")) |
| @@ -956,6 +973,7 @@ static void elan_report_contact(struct elan_tp_data *data, int contact_num, · 505 unmodified lines | ||
| 956 | 973 | |
| 957 | 974 | if (data->report_features & ETP_FEATURE_REPORT_MK) { |
| 958 | 975 | unsigned int mk_x, mk_y, area_x, area_y; |
| 976 | + int adj_width_x, adj_width_y; | |
| 959 | 977 | u8 mk_data = high_precision ? |
| 960 | 978 | packet[ETP_MK_DATA_OFFSET + contact_num] : |
| 961 | 979 | finger_data[3]; |
| @@ -967,8 +985,14 @@ static void elan_report_contact(struct elan_tp_data *data, int contact_num, · 5 unmodified lines | ||
| 967 | 985 | * To avoid treating large finger as palm, let's reduce |
| 968 | 986 | * the width x and y per trace. |
| 969 | 987 | */ |
| 970 | − area_x = mk_x * (data->width_x - ETP_FWIDTH_REDUCE); | |
| 971 | − area_y = mk_y * (data->width_y - ETP_FWIDTH_REDUCE); | |
| 988 | + | |
| 989 | + adj_width_x = data->width_x > ETP_FWIDTH_REDUCE ? | |
| 990 | + data->width_x - ETP_FWIDTH_REDUCE : 0; | |
| 991 | + adj_width_y = data->width_y > ETP_FWIDTH_REDUCE ? | |
| 992 | + data->width_y - ETP_FWIDTH_REDUCE : 0; | |
| 993 | + | |
| 994 | + area_x = mk_x * adj_width_x; | |
| 995 | + area_y = mk_y * adj_width_y; | |
| 972 | 996 | |
| 973 | 997 | input_report_abs(input, ABS_TOOL_WIDTH, mk_x); |
| 974 | 998 | input_report_abs(input, ABS_MT_TOUCH_MAJOR, |