[PATCH 4.14 28/31] staging: greybus: spilib: fix use-after-free after deregistration

From: Greg Kroah-Hartman
Date: Sun Nov 19 2017 - 10:01:33 EST


4.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@xxxxxxxxxx>

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@xxxxxxxxxx>
Reviewed-by: Rui Miguel Silva <rmfrfs@xxxxxxxxx>
Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/staging/greybus/spilib.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/staging/greybus/spilib.c
+++ b/drivers/staging/greybus/spilib.c
@@ -544,12 +544,15 @@ int gb_spilib_master_init(struct gb_conn

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_con
struct spi_master *master = gb_connection_get_data(connection);

spi_unregister_master(master);
- spi_master_put(master);
}
EXPORT_SYMBOL_GPL(gb_spilib_master_exit);