HID: fix data access in implement()

[firefly-linux-kernel-4.4.55.git] / drivers / hid / hid-core.c

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index b0f2f459f59bb8dc6df5d1d305824ae27e1ce77b..a1b248cea5b093fedfca3e1f5c6e9344a4e9f10e 100644 (file)
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1128,7 +1128,8 @@ static void hid_output_field(const struct hid_device *hid,
 }
 
 /*
- * Create a report.
+ * Create a report. 'data' has to be allocated using
+ * hid_alloc_report_buf() so that it has proper size.
  */
 
 void hid_output_report(struct hid_report *report, __u8 *data)
@@ -1144,6 +1145,22 @@ void hid_output_report(struct hid_report *report, __u8 *data)
 }
 EXPORT_SYMBOL_GPL(hid_output_report);
 
+/*
+ * Allocator for buffer that is going to be passed to hid_output_report()
+ */
+u8 *hid_alloc_report_buf(struct hid_report *report, gfp_t flags)
+{
+       /*
+        * 7 extra bytes are necessary to achieve proper functionality
+        * of implement() working on 8 byte chunks
+        */
+
+       int len = ((report->size - 1) >> 3) + 1 + (report->id > 0) + 7;
+
+       return kmalloc(len, flags);
+}
+EXPORT_SYMBOL_GPL(hid_alloc_report_buf);
+
 /*
  * Set a field value. The report this field belongs to has to be
  * created and transferred to the device, to set this value in the