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

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>

1 files changed, 22 insertions, 6 deletions

diff --git a/drivers/hid/hid-rmi.c b/drivers/hid/hid-rmi.c
index 2c3524bacca6..0dc25142f451 100644
--- 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;