staging: greybus: spilib: fix use-after-free after deregistration

BugLink: http://bugs.launchpad.net/bugs/1744212
commit 770b03c2ca4aa44d226cf248f86aa23e546147d0 upstream.

Remove erroneous spi_master_put() after controller deregistration which
would access the already freed spi controller.

Note that spi_unregister_master() drops our only controller reference.

Fixes: ba3e67001b42 ("greybus: SPI: convert to a gpbridge driver")
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Rui Miguel Silva <rmfrfs@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/staging/greybus/spilib.c b/drivers/staging/greybus/spilib.c
index e97b1914849711f97ede40aac606aa01a34240f2..1e7321a1404cc104077af974a2e3d16ad92b5cbc 100644 (file)
--- a/drivers/staging/greybus/spilib.c
+++ b/drivers/staging/greybus/spilib.c
@@ -544,11 +544,14 @@ int gb_spilib_master_init(struct gb_connection *connection, struct device *dev,
 
        return 0;
 
-exit_spi_unregister:
-       spi_unregister_master(master);
 exit_spi_put:
        spi_master_put(master);
 
+       return ret;
+
+exit_spi_unregister:
+       spi_unregister_master(master);
+
        return ret;
 }
 EXPORT_SYMBOL_GPL(gb_spilib_master_init);
@@ -558,7 +561,6 @@ void gb_spilib_master_exit(struct gb_connection *connection)
        struct spi_master *master = gb_connection_get_data(connection);
 
        spi_unregister_master(master);
-       spi_master_put(master);
 }
 EXPORT_SYMBOL_GPL(gb_spilib_master_exit);