HID: hyperv: make sure input buffer is big enough

We need at least HID_MAX_BUFFER_SIZE (4096) bytes as input buffer. HID
core depends on this as it requires every input report to be at least as
big as advertised.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 8 insertions, 3 deletions

diff --git a/drivers/hid/hid-hyperv.c b/drivers/hid/hid-hyperv.c
index 8fae6d1414cc..c24908f14934 100644
--- a/drivers/hid/hid-hyperv.c
+++ b/drivers/hid/hid-hyperv.c
@@ -157,6 +157,7 @@ struct mousevsc_dev {
         u32                     report_desc_size;
         struct hv_input_dev_info hid_dev_info;
         struct hid_device       *hid_device;
+        u8                      input_buf[HID_MAX_BUFFER_SIZE];
 };
 
 
@@ -256,6 +257,7 @@ static void mousevsc_on_receive(struct hv_device *device,
         struct synthhid_msg *hid_msg;
         struct mousevsc_dev *input_dev = hv_get_drvdata(device);
         struct synthhid_input_report *input_report;
+        size_t len;
 
         pipe_msg = (struct pipe_prt_msg *)((unsigned long)packet +
                                                 (packet->offset8 << 3));
@@ -300,9 +302,12 @@ static void mousevsc_on_receive(struct hv_device *device,
                         (struct synthhid_input_report *)pipe_msg->data;
                 if (!input_dev->init_complete)
                         break;
-                hid_input_report(input_dev->hid_device,
-                                HID_INPUT_REPORT, input_report->buffer,
-                                input_report->header.size, 1);
+
+                len = min(input_report->header.size,
+                          (u32)sizeof(input_dev->input_buf));
+                memcpy(input_dev->input_buf, input_report->buffer, len);
+                hid_input_report(input_dev->hid_device, HID_INPUT_REPORT,
+                                 input_dev->input_buf, len, 1);
                 break;
         default:
                 pr_err("unsupported hid msg type - type %d len %d",