Merge tag 'scmi-fixes-6.12-2' of https://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into HEAD

Arm SCMI fixes for v6.12(part 2)

Couple of fixes to address slab-use-after-free in scmi_bus_notifier()
via scmi_dev->name and possible incorrect clear channel transport
operation on A2P channel if some sort of P2A only messages are initiated
on A2P channel(occurs when stress tested passing /dev/random to the
channel).

Apart from this, there are fixes to address missing "arm" prefix in the
recently added property max-rx-timeout-ms which was missed in the review
but was identified when further additions to the same binding were
getting reviewed.

* tag 'scmi-fixes-6.12-2' of https://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux:
  firmware: arm_scmi: Use vendor string in max-rx-timeout-ms
  dt-bindings: firmware: arm,scmi: Add missing vendor string
  firmware: arm_scmi: Reject clear channel request on A2P
  firmware: arm_scmi: Fix slab-use-after-free in scmi_bus_notifier()

Link: https://lore.kernel.org/r/20241031172734.3109140-1-sudeep.holla@arm.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

3 files changed, 14 insertions, 5 deletions

diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index 96b2e5f9a8ef..157172a5f2b5 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -325,7 +325,10 @@ EXPORT_SYMBOL_GPL(scmi_driver_unregister);
 
 static void scmi_device_release(struct device *dev)
 {
-	kfree(to_scmi_dev(dev));
+	struct scmi_device *scmi_dev = to_scmi_dev(dev);
+
+	kfree_const(scmi_dev->name);
+	kfree(scmi_dev);
 }
 
 static void __scmi_device_destroy(struct scmi_device *scmi_dev)
@@ -338,7 +341,6 @@ static void __scmi_device_destroy(struct scmi_device *scmi_dev)
 	if (scmi_dev->protocol_id == SCMI_PROTOCOL_SYSTEM)
 		atomic_set(&scmi_syspower_registered, 0);
 
-	kfree_const(scmi_dev->name);
 	ida_free(&scmi_bus_id, scmi_dev->id);
 	device_unregister(&scmi_dev->dev);
 }
@@ -410,7 +412,6 @@ __scmi_device_create(struct device_node *np, struct device *parent,
 
 	return scmi_dev;
 put_dev:
-	kfree_const(scmi_dev->name);
 	put_device(&scmi_dev->dev);
 	ida_free(&scmi_bus_id, id);
 	return NULL;
diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index c4b8e7ff88aa..cdec50a698a1 100644
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -163,6 +163,7 @@ void scmi_protocol_release(const struct scmi_handle *handle, u8 protocol_id);
  *      used to initialize this channel
  * @dev: Reference to device in the SCMI hierarchy corresponding to this
  *	 channel
+ * @is_p2a: A flag to identify a channel as P2A (RX)
  * @rx_timeout_ms: The configured RX timeout in milliseconds.
  * @handle: Pointer to SCMI entity handle
  * @no_completion_irq: Flag to indicate that this channel has no completion
@@ -174,6 +175,7 @@ void scmi_protocol_release(const struct scmi_handle *handle, u8 protocol_id);
 struct scmi_chan_info {
 	int id;
 	struct device *dev;
+	bool is_p2a;
 	unsigned int rx_timeout_ms;
 	struct scmi_handle *handle;
 	bool no_completion_irq;
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index a477b5ade38d..f8934d049d68 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -1048,6 +1048,11 @@ static inline void scmi_xfer_command_release(struct scmi_info *info,
 static inline void scmi_clear_channel(struct scmi_info *info,
 				      struct scmi_chan_info *cinfo)
 {
+	if (!cinfo->is_p2a) {
+		dev_warn(cinfo->dev, "Invalid clear on A2P channel !\n");
+		return;
+	}
+
 	if (info->desc->ops->clear_channel)
 		info->desc->ops->clear_channel(cinfo);
 }
@@ -2638,6 +2643,7 @@ static int scmi_chan_setup(struct scmi_info *info, struct device_node *of_node,
 	if (!cinfo)
 		return -ENOMEM;
 
+	cinfo->is_p2a = !tx;
 	cinfo->rx_timeout_ms = info->desc->max_rx_timeout_ms;
 
 	/* Create a unique name for this transport device */
@@ -3042,10 +3048,10 @@ static const struct scmi_desc *scmi_transport_setup(struct device *dev)
 
 	dev_info(dev, "Using %s\n", dev_driver_string(trans->supplier));
 
-	ret = of_property_read_u32(dev->of_node, "max-rx-timeout-ms",
+	ret = of_property_read_u32(dev->of_node, "arm,max-rx-timeout-ms",
 				   &trans->desc->max_rx_timeout_ms);
 	if (ret && ret != -EINVAL)
-		dev_err(dev, "Malformed max-rx-timeout-ms DT property.\n");
+		dev_err(dev, "Malformed arm,max-rx-timeout-ms DT property.\n");
 
 	dev_info(dev, "SCMI max-rx-timeout: %dms\n",
 		 trans->desc->max_rx_timeout_ms);