firmware: arm_ffa: Fix the race around setting ffa_dev->properties

Currently, ffa_dev->properties is set after the ffa_device_register()
call return in ffa_setup_partitions(). This could potentially result in
a race where the partition's properties is accessed while probing
struct ffa_device before it is set.

Update the ffa_device_register() to receive ffa_partition_info so all
the data from the partition information received from the firmware can
be updated into the struct ffa_device before the calling device_register()
in ffa_device_register().

Fixes: e781858 ("firmware: arm_ffa: Add initial FFA bus support for device enumeration")
Signed-off-by: Levi Yun <yeoreum.yun@arm.com>
Message-Id: <20241203143109.1030514-2-yeoreum.yun@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

Author: LeviYeoReum

drivers/firmware/arm_ffa/bus.c

@@ -187,13 +187,18 @@ bool ffa_device_is_valid(struct ffa_device *ffa_dev)
 	return valid;
 }
 
-struct ffa_device *ffa_device_register(const uuid_t *uuid, int vm_id,
-				       const struct ffa_ops *ops)
+struct ffa_device *
+ffa_device_register(const struct ffa_partition_info *part_info,
+		    const struct ffa_ops *ops)
 {
 	int id, ret;
+	uuid_t uuid;
 	struct device *dev;
 	struct ffa_device *ffa_dev;
 
+	if (!part_info)
+		return NULL;
+
 	id = ida_alloc_min(&ffa_bus_id, 1, GFP_KERNEL);
 	if (id < 0)
 		return NULL;
@@ -210,9 +215,11 @@ struct ffa_device *ffa_device_register(const uuid_t *uuid, int vm_id,
 	dev_set_name(&ffa_dev->dev, "arm-ffa-%d", id);
 
 	ffa_dev->id = id;
-	ffa_dev->vm_id = vm_id;
+	ffa_dev->vm_id = part_info->id;
+	ffa_dev->properties = part_info->properties;
 	ffa_dev->ops = ops;
-	uuid_copy(&ffa_dev->uuid, uuid);
+	import_uuid(&uuid, (u8 *)part_info->uuid);
+	uuid_copy(&ffa_dev->uuid, &uuid);
 
 	ret = device_register(&ffa_dev->dev);
 	if (ret) {

drivers/firmware/arm_ffa/driver.c

@@ -1387,7 +1387,6 @@ static struct notifier_block ffa_bus_nb = {
 static int ffa_setup_partitions(void)
 {
 	int count, idx, ret;
-	uuid_t uuid;
 	struct ffa_device *ffa_dev;
 	struct ffa_dev_part_info *info;
 	struct ffa_partition_info *pbuf, *tpbuf;
@@ -1406,23 +1405,19 @@ static int ffa_setup_partitions(void)
 
 	xa_init(&drv_info->partition_info);
 	for (idx = 0, tpbuf = pbuf; idx < count; idx++, tpbuf++) {
-		import_uuid(&uuid, (u8 *)tpbuf->uuid);
-
 		/* Note that if the UUID will be uuid_null, that will require
 		 * ffa_bus_notifier() to find the UUID of this partition id
 		 * with help of ffa_device_match_uuid(). FF-A v1.1 and above
 		 * provides UUID here for each partition as part of the
 		 * discovery API and the same is passed.
 		 */
-		ffa_dev = ffa_device_register(&uuid, tpbuf->id, &ffa_drv_ops);
+		ffa_dev = ffa_device_register(tpbuf, &ffa_drv_ops);
 		if (!ffa_dev) {
 			pr_err("%s: failed to register partition ID 0x%x\n",
 			       __func__, tpbuf->id);
 			continue;
 		}
 
-		ffa_dev->properties = tpbuf->properties;
-
 		if (drv_info->version > FFA_VERSION_1_0 &&
 		    !(tpbuf->properties & FFA_PARTITION_AARCH64_EXEC))
 			ffa_mode_32bit_set(ffa_dev);

include/linux/arm_ffa.h

@@ -166,19 +166,22 @@ static inline void *ffa_dev_get_drvdata(struct ffa_device *fdev)
 	return dev_get_drvdata(&fdev->dev);
 }
 
+struct ffa_partition_info;
+
 #if IS_REACHABLE(CONFIG_ARM_FFA_TRANSPORT)
-struct ffa_device *ffa_device_register(const uuid_t *uuid, int vm_id,
-				       const struct ffa_ops *ops);
+struct ffa_device *
+ffa_device_register(const struct ffa_partition_info *part_info,
+		    const struct ffa_ops *ops);
 void ffa_device_unregister(struct ffa_device *ffa_dev);
 int ffa_driver_register(struct ffa_driver *driver, struct module *owner,
 			const char *mod_name);
 void ffa_driver_unregister(struct ffa_driver *driver);
 bool ffa_device_is_valid(struct ffa_device *ffa_dev);
 
 #else
-static inline
-struct ffa_device *ffa_device_register(const uuid_t *uuid, int vm_id,
-				       const struct ffa_ops *ops)
+static inline struct ffa_device *
+ffa_device_register(const struct ffa_partition_info *part_info,
+		    const struct ffa_ops *ops)
 {
 	return NULL;
 }