[PATCH 1/6] bus: fsl-mc: fix double-free on mc_dev

[Ioana Ciornei]

The blamed commit tried to simplify how the deallocations are done but,
in the process, introduced a double-free on the mc_dev variable.

In case the MC device is a DPRC, a new mc_bus is allocated and the
mc_dev variable is just a reference to one of its fields. In this
circumstance, on the error path only the mc_bus should be freed.

This commit introduces back the following checkpatch warning which is a
false-positive.

WARNING: kfree(NULL) is safe and this check is probably not required
+       if (mc_bus)
+               kfree(mc_bus);

Fixes: a042fbed0290 ("staging: fsl-mc: simplify couple of deallocations")
Signed-off-by: Ioana Ciornei <ioana.ciornei at nxp.com>
---
 drivers/bus/fsl-mc/fsl-mc-bus.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c
index a8be8cf246fb..0c3a38d7f335 100644
--- a/drivers/bus/fsl-mc/fsl-mc-bus.c
+++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
@@ -906,8 +906,10 @@ int fsl_mc_device_add(struct fsl_mc_obj_desc *obj_desc,
 
 error_cleanup_dev:
 	kfree(mc_dev->regions);
-	kfree(mc_bus);
-	kfree(mc_dev);
+	if (mc_bus)
+		kfree(mc_bus);
+	else
+		kfree(mc_dev);
 
 	return error;
 }
-- 
2.34.1