Input: synaptics-rmi4 - do not consume more data than we have (F11, F12)

commit 5d40d95e7e64756cc30606c2ba169271704d47cb upstream.

Currently, rmi_f11_attention() and rmi_f12_attention() functions update
the attn_data data pointer and size based on the size of the expected
size of the attention data. However, if the actual valid data in the
attn buffer is less then the expected value then the updated data
pointer will point to memory beyond the end of the attn buffer. Using
the calculated valid_bytes instead will prevent this from happening.
Signed-off-by: NAndrew Duggan <aduggan@synaptics.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20191025002527.3189-3-aduggan@synaptics.comSigned-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/input/rmi4/rmi_f11.c

@@ -1287,8 +1287,8 @@ static irqreturn_t rmi_f11_attention(int irq, void *ctx)
 			valid_bytes = f11->sensor.attn_size;
 		memcpy(f11->sensor.data_pkt, drvdata->attn_data.data,
 			valid_bytes);
-		drvdata->attn_data.data += f11->sensor.attn_size;
-		drvdata->attn_data.size -= f11->sensor.attn_size;
+		drvdata->attn_data.data += valid_bytes;
+		drvdata->attn_data.size -= valid_bytes;
 	} else {
 		error = rmi_read_block(rmi_dev,
 				data_base_addr, f11->sensor.data_pkt,

drivers/input/rmi4/rmi_f12.c

@@ -217,8 +217,8 @@ static irqreturn_t rmi_f12_attention(int irq, void *ctx)
 			valid_bytes = sensor->attn_size;
 		memcpy(sensor->data_pkt, drvdata->attn_data.data,
 			valid_bytes);
-		drvdata->attn_data.data += sensor->attn_size;
-		drvdata->attn_data.size -= sensor->attn_size;
+		drvdata->attn_data.data += valid_bytes;
+		drvdata->attn_data.size -= valid_bytes;
 	} else {
 		retval = rmi_read_block(rmi_dev, f12->data_addr,
 					sensor->data_pkt, sensor->pkt_size);