mcb: fix error handling in mcb_alloc_bus()

There are two bugs:
1) If ida_simple_get() fails then this code calls put_device(carrier)
   but we haven't yet called get_device(carrier) and probably that
   leads to a use after free.
2) After device_initialize() then we need to use put_device() to
   release the bus.  This will free the internal resources tied to the
   device and call mcb_free_bus() which will free the rest.

Fixes: 5d9e2ab9fea4 ("mcb: Implement bus->dev.release callback")
Fixes: 18d288198099 ("mcb: Correctly initialize the bus's device")
Cc: stable@vger.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Johannes Thumshirn <jth@kernel.org>
Link: https://lore.kernel.org/r/32e160cf6864ce77f9d62948338e24db9fd8ead9.1630931319.git.johannes.thumshirn@wdc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/mcb/mcb-core.c b/drivers/mcb/mcb-core.c
index edf4ee6..cf128b3 100644 (file)
--- a/drivers/mcb/mcb-core.c
+++ b/drivers/mcb/mcb-core.c
@@ -275,8 +275,8 @@ struct mcb_bus *mcb_alloc_bus(struct device *carrier)
 
        bus_nr = ida_simple_get(&mcb_ida, 0, 0, GFP_KERNEL);
        if (bus_nr < 0) {
-               rc = bus_nr;
-               goto err_free;
+               kfree(bus);
+               return ERR_PTR(bus_nr);
        }
 
        bus->bus_nr = bus_nr;
@@ -291,12 +291,12 @@ struct mcb_bus *mcb_alloc_bus(struct device *carrier)
        dev_set_name(&bus->dev, "mcb:%d", bus_nr);
        rc = device_add(&bus->dev);
        if (rc)
-               goto err_free;
+               goto err_put;
 
        return bus;
-err_free:
-       put_device(carrier);
-       kfree(bus);
+
+err_put:
+       put_device(&bus->dev);
        return ERR_PTR(rc);
 }
 EXPORT_SYMBOL_NS_GPL(mcb_alloc_bus, MCB);