[PATCH 4.14 052/118] sfp: fix sfp-bus oops when removing socket/upstream

[Greg Kroah-Hartman]

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

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

From: Russell King <rmk+ker...@armlinux.org.uk>


[ Upstream commit 0b2122e4934c7783d336397864e34ee53aad0965 ]

When we remove a socket or upstream, and the other side isn't
registered, we dereference a NULL pointer, causing a kernel oops.
Fix this.

Fixes: ce0aa27ff3f6 ("sfp: add sfp-bus to bridge between network devices and 
sfp cages")
Signed-off-by: Russell King <rmk+ker...@armlinux.org.uk>
Reviewed-by: Florian Fainelli <f.faine...@gmail.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/net/phy/sfp-bus.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/net/phy/sfp-bus.c
+++ b/drivers/net/phy/sfp-bus.c
@@ -359,7 +359,8 @@ EXPORT_SYMBOL_GPL(sfp_register_upstream)
 void sfp_unregister_upstream(struct sfp_bus *bus)
 {
        rtnl_lock();
-       sfp_unregister_bus(bus);
+       if (bus->sfp)
+               sfp_unregister_bus(bus);
        bus->upstream = NULL;
        bus->netdev = NULL;
        rtnl_unlock();
@@ -464,7 +465,8 @@ EXPORT_SYMBOL_GPL(sfp_register_socket);
 void sfp_unregister_socket(struct sfp_bus *bus)
 {
        rtnl_lock();
-       sfp_unregister_bus(bus);
+       if (bus->netdev)
+               sfp_unregister_bus(bus);
        bus->sfp_dev = NULL;
        bus->sfp = NULL;
        bus->socket_ops = NULL;