[PATCH v7 12/12] rpmsg: Fix kfree() of static memory on setting driver_override

Krzysztof Kozlowski
2022-04-19T11:35:30Z

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")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---
drivers/rpmsg/rpmsg_internal.h | 13 +++++++++++--
drivers/rpmsg/rpmsg_ns.c | 14 ++++++++++++--
include/linux/rpmsg.h | 6 ++++--
3 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
index d4b23fd019a8..3e81642238d2 100644
--- 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 762ff1ae279f..8eb8f328237e 100644
--- 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 02fa9116cd60..20c8cd1cde21 100644
--- 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;
--
2.32.0