[PATCH 4.19 018/422] Input: synaptics-rmi4 - do not consume more data than we have (F11, F12)

[Greg Kroah-Hartman]

From: Andrew Duggan <aduggan@xxxxxxxxxxxxx>

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: Andrew Duggan <aduggan@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20191025002527.3189-3-aduggan@xxxxxxxxxxxxx
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/input/rmi4/rmi_f11.c |    4 ++--
 drivers/input/rmi4/rmi_f12.c |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/input/rmi4/rmi_f11.c
+++ b/drivers/input/rmi4/rmi_f11.c
@@ -1287,8 +1287,8 @@ static irqreturn_t rmi_f11_attention(int
 			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,
--- a/drivers/input/rmi4/rmi_f12.c
+++ b/drivers/input/rmi4/rmi_f12.c
@@ -217,8 +217,8 @@ static irqreturn_t rmi_f12_attention(int
 			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);