HID: rmi: check that report ids exist in the report_id_hash before accessing their...

It is possible that the hid-rmi driver could get loaded onto a device which does not have the
expected report ids. This should not happen because it would indicate that the hid-rmi driver is
not compatible with that device. However, if it does happen it should return an error from probe
instead of dereferencing a null pointer.

related bug:
https://bugzilla.kernel.org/show_bug.cgi?id=80091

Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-rmi.c b/drivers/hid/hid-rmi.c
index 2c3524bacca6d0487d1b93f128a75e4f09647f3b..0dc25142f451ff8d5fb040249d83d811a029db1d 100644 (file)
--- a/drivers/hid/hid-rmi.c
+++ b/drivers/hid/hid-rmi.c
@@ -848,6 +848,8 @@ static int rmi_probe(struct hid_device *hdev, const struct hid_device_id *id)
        struct rmi_data *data = NULL;
        int ret;
        size_t alloc_size;
+       struct hid_report *input_report;
+       struct hid_report *output_report;
 
        data = devm_kzalloc(&hdev->dev, sizeof(struct rmi_data), GFP_KERNEL);
        if (!data)
@@ -866,12 +868,26 @@ static int rmi_probe(struct hid_device *hdev, const struct hid_device_id *id)
                return ret;
        }
 
-       data->input_report_size = (hdev->report_enum[HID_INPUT_REPORT]
-               .report_id_hash[RMI_ATTN_REPORT_ID]->size >> 3)
-               + 1 /* report id */;
-       data->output_report_size = (hdev->report_enum[HID_OUTPUT_REPORT]
-               .report_id_hash[RMI_WRITE_REPORT_ID]->size >> 3)
-               + 1 /* report id */;
+       input_report = hdev->report_enum[HID_INPUT_REPORT]
+                       .report_id_hash[RMI_ATTN_REPORT_ID];
+       if (!input_report) {
+               hid_err(hdev, "device does not have expected input report\n");
+               ret = -ENODEV;
+               return ret;
+       }
+
+       data->input_report_size = (input_report->size >> 3) + 1 /* report id */;
+
+       output_report = hdev->report_enum[HID_OUTPUT_REPORT]
+                       .report_id_hash[RMI_WRITE_REPORT_ID];
+       if (!output_report) {
+               hid_err(hdev, "device does not have expected output report\n");
+               ret = -ENODEV;
+               return ret;
+       }
+
+       data->output_report_size = (output_report->size >> 3)
+                                       + 1 /* report id */;
 
        alloc_size = data->output_report_size + data->input_report_size;