mei: fix possible integer overflow issue

There is a possible integer overflow following by a buffer overflow
when accumulating messages coming from the FW to compose a full payload.
Occurrence of wrap around has to be prevented for next message size
calculation.
For unsigned integer the addition overflow has occurred when the
result is smaller than one of the arguments.
To simplify the fix, the types of buf.size and buf_idx are set to the
same width, namely size_t also to be aligned with the type of length
parameter in file read/write ops.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/misc/mei/mei_dev.h b/drivers/misc/mei/mei_dev.h
index da613268480c..9b793f87b7d4 100644
--- a/drivers/misc/mei/mei_dev.h
+++ b/drivers/misc/mei/mei_dev.h
@@ -126,7 +126,7 @@ enum mei_cb_file_ops {
  * Intel MEI message data struct
  */
 struct mei_msg_data {
-	u32 size;
+	size_t size;
 	unsigned char *data;
 };
 
@@ -190,7 +190,7 @@ struct mei_cl_cb {
 	struct mei_cl *cl;
 	enum mei_cb_file_ops fop_type;
 	struct mei_msg_data buf;
-	unsigned long buf_idx;
+	size_t buf_idx;
 	unsigned long read_time;
 	struct file *file_object;
 	int status;