rpmsg: Fix kfree() of static memory on setting driver_override

The driver_override field from platform driver should not be initialized
from static memory (string literal) because the core later kfree() it,
for example when driver_override is set via sysfs.

Use dedicated helper to set driver_override properly.

Fixes: 950a7388f02b ("rpmsg: Turn name service into a stand alone driver")
Fixes: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface")
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220419113435.246203-13-krzysztof.kozlowski@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
index d4b23fd..3e81642 100644 (file)
--- a/drivers/rpmsg/rpmsg_internal.h
+++ b/drivers/rpmsg/rpmsg_internal.h
@@ -94,10 +94,19 @@ int rpmsg_release_channel(struct rpmsg_device *rpdev,
  */
 static inline int rpmsg_ctrldev_register_device(struct rpmsg_device *rpdev)
 {
+       int ret;
+
        strcpy(rpdev->id.name, "rpmsg_ctrl");
-       rpdev->driver_override = "rpmsg_ctrl";
+       ret = driver_set_override(&rpdev->dev, &rpdev->driver_override,
+                                 rpdev->id.name, strlen(rpdev->id.name));
+       if (ret)
+               return ret;
+
+       ret = rpmsg_register_device(rpdev);
+       if (ret)
+               kfree(rpdev->driver_override);
 
-       return rpmsg_register_device(rpdev);
+       return ret;
 }
 
 #endif

diff --git a/drivers/rpmsg/rpmsg_ns.c b/drivers/rpmsg/rpmsg_ns.c
index 762ff1a..8eb8f32 100644 (file)
--- a/drivers/rpmsg/rpmsg_ns.c
+++ b/drivers/rpmsg/rpmsg_ns.c
@@ -20,12 +20,22 @@
  */
 int rpmsg_ns_register_device(struct rpmsg_device *rpdev)
 {
+       int ret;
+
        strcpy(rpdev->id.name, "rpmsg_ns");
-       rpdev->driver_override = "rpmsg_ns";
+       ret = driver_set_override(&rpdev->dev, &rpdev->driver_override,
+                                 rpdev->id.name, strlen(rpdev->id.name));
+       if (ret)
+               return ret;
+
        rpdev->src = RPMSG_NS_ADDR;
        rpdev->dst = RPMSG_NS_ADDR;
 
-       return rpmsg_register_device(rpdev);
+       ret = rpmsg_register_device(rpdev);
+       if (ret)
+               kfree(rpdev->driver_override);
+
+       return ret;
 }
 EXPORT_SYMBOL(rpmsg_ns_register_device);
 

diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
index 02fa911..20c8cd1 100644 (file)
--- a/include/linux/rpmsg.h
+++ b/include/linux/rpmsg.h
@@ -41,7 +41,9 @@ struct rpmsg_channel_info {
  * rpmsg_device - device that belong to the rpmsg bus
  * @dev: the device struct
  * @id: device id (used to match between rpmsg drivers and devices)
- * @driver_override: driver name to force a match
+ * @driver_override: driver name to force a match; do not set directly,
+ *                   because core frees it; use driver_set_override() to
+ *                   set or clear it.
  * @src: local address
  * @dst: destination address
  * @ept: the rpmsg endpoint of this channel
@@ -51,7 +53,7 @@ struct rpmsg_channel_info {
 struct rpmsg_device {
        struct device dev;
        struct rpmsg_device_id id;
-       char *driver_override;
+       const char *driver_override;
        u32 src;
        u32 dst;
        struct rpmsg_endpoint *ept;