soundwire: fix port_ready[] dynamic allocation in mipi_disco

The existing code allocates memory for the total number of ports.
This only works if the ports are contiguous, but will break if e.g. a
Devices uses port0, 1, and 14. The port_ready[] array would contain 3
elements, which would lead to an out-of-bounds access. Conversely in
other cases, the wrong port index would be used leading to timeouts on
prepare.

This can be fixed by allocating for the worst-case of 15
ports (DP0..DP14). In addition since the number is now fixed, we can
use an array instead of a dynamic allocation.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Link: https://lore.kernel.org/r/20200831134318.11443-4-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/mipi_disco.c

@@ -289,7 +289,7 @@ int sdw_slave_read_prop(struct sdw_slave *slave)
 	struct sdw_slave_prop *prop = &slave->prop;
 	struct device *dev = &slave->dev;
 	struct fwnode_handle *port;
-	int num_of_ports, nval, i, dp0 = 0;
+	int nval;
 
 	device_property_read_u32(dev, "mipi-sdw-sw-interface-revision",
 				 &prop->mipi_revision);
@@ -352,7 +352,6 @@ int sdw_slave_read_prop(struct sdw_slave *slave)
 			return -ENOMEM;
 
 		sdw_slave_read_dp0(slave, port, prop->dp0_prop);
-		dp0 = 1;
 	}
 
 	/*
@@ -383,21 +382,6 @@ int sdw_slave_read_prop(struct sdw_slave *slave)
 	sdw_slave_read_dpn(slave, prop->sink_dpn_prop, nval,
 			   prop->sink_ports, "sink");
 
-	/* some ports are bidirectional so check total ports by ORing */
-	nval = prop->source_ports | prop->sink_ports;
-	num_of_ports = hweight32(nval) + dp0; /* add DP0 */
-
-	/* Allocate port_ready based on num_of_ports */
-	slave->port_ready = devm_kcalloc(&slave->dev, num_of_ports,
-					 sizeof(*slave->port_ready),
-					 GFP_KERNEL);
-	if (!slave->port_ready)
-		return -ENOMEM;
-
-	/* Initialize completion */
-	for (i = 0; i < num_of_ports; i++)
-		init_completion(&slave->port_ready[i]);
-
 	return 0;
 }
 EXPORT_SYMBOL(sdw_slave_read_prop);

drivers/soundwire/slave.c

@@ -25,6 +25,7 @@ static int sdw_slave_add(struct sdw_bus *bus,
 {
 	struct sdw_slave *slave;
 	int ret;
+	int i;
 
 	slave = kzalloc(sizeof(*slave), GFP_KERNEL);
 	if (!slave)
@@ -58,6 +59,9 @@ static int sdw_slave_add(struct sdw_bus *bus,
 	init_completion(&slave->probe_complete);
 	slave->probed = false;
 
+	for (i = 0; i < SDW_MAX_PORTS; i++)
+		init_completion(&slave->port_ready[i]);
+
 	mutex_lock(&bus->bus_lock);
 	list_add_tail(&slave->node, &bus->slaves);
 	mutex_unlock(&bus->bus_lock);

include/linux/soundwire/sdw.h

@@ -619,7 +619,7 @@ struct sdw_slave {
 	struct dentry *debugfs;
 #endif
 	struct list_head node;
-	struct completion *port_ready;
+	struct completion port_ready[SDW_MAX_PORTS];
 	enum sdw_clk_stop_mode curr_clk_stop_mode;
 	u16 dev_num;
 	u16 dev_num_sticky;