[PATCH] driver: core: Prevent NULL pointer dereference in device name functions
From: Alexander Sverdlin
Date: Sun Feb 12 2023 - 17:05:00 EST
Prevent similar scenarios:
Unable to handle kernel NULL pointer dereference at virtual address 00000038
...
PC is at dev_driver_string+0x0/0x38
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx>
---
drivers/base/core.c | 3 +++
include/linux/device.h | 5 +++++
2 files changed, 8 insertions(+)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index a3e14143ec0c..4ff2ddea7c9b 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -2174,6 +2174,9 @@ const char *dev_driver_string(const struct device *dev)
{
struct device_driver *drv;
+ if (!dev)
+ return "<null>";
+
/* dev->driver can change to NULL underneath us because of unbinding,
* so be careful about accessing it. dev->bus and dev->class should
* never change once they are set, so they don't need special care.
diff --git a/include/linux/device.h b/include/linux/device.h
index 44e3acae7b36..ff9e19e6d78c 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -696,6 +696,9 @@ static inline bool device_iommu_mapped(struct device *dev)
static inline const char *dev_name(const struct device *dev)
{
+ if (!dev)
+ return "<null>";
+
/* Use the init name until the kobject becomes available */
if (dev->init_name)
return dev->init_name;
@@ -712,6 +715,8 @@ static inline const char *dev_name(const struct device *dev)
*/
static inline const char *dev_bus_name(const struct device *dev)
{
+ if (!dev)
+ return "<null>";
return dev->bus ? dev->bus->name : (dev->class ? dev->class->name : "");
}
--
2.39.1