[PATCH V4 02/14] i3c: Fix unlocked dereference of dev->desc in i3c_device_get_supported_xfer_mode()

[Adrian Hunter <adrian.hunter@intel.com>]

i3c_device_get_supported_xfer_mode() uses dev->desc to obtain the
master controller.  However, dev->desc must not be dereferenced unless
bus->lock is held, and this function does not take that lock.

The function only needs access to the master controller associated with
the device's bus.  Use dev->bus instead, which is always valid for the
lifetime of the device and does not require dereferencing dev->desc.

Fixes: 256a21743d91 ("i3c: Add HDR API support")
Cc: stable@vger.kernel.org
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---


Changes in V4:

	None

Changes in V3:

	New patch


 drivers/i3c/device.c    | 2 +-
 drivers/i3c/internals.h | 5 +++++
 drivers/i3c/master.c    | 6 ------
 3 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/i3c/device.c b/drivers/i3c/device.c
index 101eaa77de68..a3778282e84c 100644
--- a/drivers/i3c/device.c
+++ b/drivers/i3c/device.c
@@ -309,7 +309,7 @@ EXPORT_SYMBOL_GPL(i3c_device_match_id);
  */
 u32 i3c_device_get_supported_xfer_mode(struct i3c_device *dev)
 {
-	return i3c_dev_get_master(dev->desc)->this->info.hdr_cap | BIT(I3C_SDR);
+	return i3c_bus_to_i3c_master(dev->bus)->this->info.hdr_cap | BIT(I3C_SDR);
 }
 EXPORT_SYMBOL_GPL(i3c_device_get_supported_xfer_mode);
 
diff --git a/drivers/i3c/internals.h b/drivers/i3c/internals.h
index 0f1f3f766623..86a36b951e0d 100644
--- a/drivers/i3c/internals.h
+++ b/drivers/i3c/internals.h
@@ -72,4 +72,9 @@ static inline void i3c_readl_fifo(const void __iomem *addr, void *buf,
 	}
 }
 
+static inline struct i3c_master_controller *i3c_bus_to_i3c_master(struct i3c_bus *i3cbus)
+{
+	return container_of(i3cbus, struct i3c_master_controller, bus);
+}
+
 #endif /* I3C_INTERNAL_H */
diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index d2fb1a110521..c7bb52b71d88 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -102,12 +102,6 @@ void i3c_bus_normaluse_unlock(struct i3c_bus *bus)
 	up_read(&bus->lock);
 }
 
-static struct i3c_master_controller *
-i3c_bus_to_i3c_master(struct i3c_bus *i3cbus)
-{
-	return container_of(i3cbus, struct i3c_master_controller, bus);
-}
-
 static struct i3c_master_controller *dev_to_i3cmaster(struct device *dev)
 {
 	return container_of(dev, struct i3c_master_controller, dev);
-- 
2.53.0