I had to go twice through the history to get a grasp at this code. De-duplicate the various tests in one common helper to make it more explicit. Note that the `HID_UP_KEYBOARD + 1` condition is tested through https://gitlab.freedesktop.org/libevdev/hid-tools/-/merge_requests/121 Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> --- drivers/hid/hid-core.c | 54 ++++++++++++++++++++++++++++++------------ 1 file changed, 39 insertions(+), 15 deletions(-) diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index 75e7b8447bf7..fad4dbdf6391 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1525,6 +1525,24 @@ static void hid_process_event(struct hid_device *hid, struct hid_field *field, hid->hiddev_hid_event(hid, field, usage, value); } +/* + * Checks if the given value is valid within this field + */ +static inline int hid_array_value_is_valid(struct hid_field *field, + __s32 value) +{ + __s32 min = field->logical_minimum; + + /* + * Value needs to be between logical min and max, and + * (value - min) is used as an index in the usage array. + * This array is of size field->maxusage + */ + return value >= min && + value <= field->logical_maximum && + value - min < field->maxusage; +} + /* * Analyse a received field, and fetch the data from it. The field * content is stored for next report processing (we do differential @@ -1539,7 +1557,6 @@ static void hid_input_field(struct hid_device *hid, struct hid_field *field, unsigned offset = field->report_offset; unsigned size = field->report_size; __s32 min = field->logical_minimum; - __s32 max = field->logical_maximum; __s32 *value; value = field->new_value; @@ -1554,8 +1571,7 @@ static void hid_input_field(struct hid_device *hid, struct hid_field *field, /* Ignore report if ErrorRollOver */ if (!(field->flags & HID_MAIN_ITEM_VARIABLE) && - value[n] >= min && value[n] <= max && - value[n] - min < field->maxusage && + hid_array_value_is_valid(field, value[n]) && field->usage[value[n] - min].hid == HID_UP_KEYBOARD + 1) return; } @@ -1563,21 +1579,29 @@ static void hid_input_field(struct hid_device *hid, struct hid_field *field, for (n = 0; n < count; n++) { if (HID_MAIN_ITEM_VARIABLE & field->flags) { - hid_process_event(hid, field, &field->usage[n], value[n], interrupt); + hid_process_event(hid, + field, + &field->usage[n], + value[n], + interrupt); continue; } - if (field->value[n] >= min && field->value[n] <= max - && field->value[n] - min < field->maxusage - && field->usage[field->value[n] - min].hid - && search(value, field->value[n], count)) - hid_process_event(hid, field, &field->usage[field->value[n] - min], 0, interrupt); - - if (value[n] >= min && value[n] <= max - && value[n] - min < field->maxusage - && field->usage[value[n] - min].hid - && search(field->value, value[n], count)) - hid_process_event(hid, field, &field->usage[value[n] - min], 1, interrupt); + if (hid_array_value_is_valid(field, field->value[n]) && + search(value, field->value[n], count)) + hid_process_event(hid, + field, + &field->usage[field->value[n] - min], + 0, + interrupt); + + if (hid_array_value_is_valid(field, value[n]) && + search(field->value, value[n], count)) + hid_process_event(hid, + field, + &field->usage[value[n] - min], + 1, + interrupt); } memcpy(field->value, value, count * sizeof(__s32)); -- 2.33.1
