sfp: fix oops with ethtool -m

Russell King · davem330 · commit 126d6848ef13 · 2018-09-18T20:14:19.000-07:00
If a network interface is created prior to the SFP socket being available, ethtool can request module information. This unfortunately leads to an oops: Unable to handle kernel NULL pointer dereference at virtual address 00000008 pgd = (ptrval) [00000008] *pgd=7c400831, *pte=00000000, *ppte=00000000 Internal error: Oops: 17 [#1] SMP ARM Modules linked in: CPU: 0 PID: 1480 Comm: ethtool Not tainted 4.19.0-rc3 torvalds#138 Hardware name: Broadcom Northstar Plus SoC PC is at sfp_get_module_info+0x8/0x10 LR is at dev_ethtool+0x218c/0x2afc Fix this by not filling in the network device's SFP bus pointer until SFP is fully bound, thereby avoiding the core calling into the SFP bus code. Fixes: ce0aa27 ("sfp: add sfp-bus to bridge between network devices and sfp cages") Reported-by: Florian Fainelli <f.fainelli@gmail.com> Tested-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/phy/sfp-bus.c b/drivers/net/phy/sfp-bus.c
@@ -349,6 +349,7 @@ static int sfp_register_bus(struct sfp_bus *bus)
 	}
 	if (bus->started)
 		bus->socket_ops->start(bus->sfp);
+	bus->netdev->sfp_bus = bus;
 	bus->registered = true;
 	return 0;
 }
@@ -357,6 +358,7 @@ static void sfp_unregister_bus(struct sfp_bus *bus)
 {
 	const struct sfp_upstream_ops *ops = bus->upstream_ops;
 
+	bus->netdev->sfp_bus = NULL;
 	if (bus->registered) {
 		if (bus->started)
 			bus->socket_ops->stop(bus->sfp);
@@ -438,7 +440,6 @@ static void sfp_upstream_clear(struct sfp_bus *bus)
 {
 	bus->upstream_ops = NULL;
 	bus->upstream = NULL;
-	bus->netdev->sfp_bus = NULL;
 	bus->netdev = NULL;
 }
 
@@ -467,7 +468,6 @@ struct sfp_bus *sfp_register_upstream(struct fwnode_handle *fwnode,
 		bus->upstream_ops = ops;
 		bus->upstream = upstream;
 		bus->netdev = ndev;
-		ndev->sfp_bus = bus;
 
 		if (bus->sfp) {
 			ret = sfp_register_bus(bus);

Original file line number	Diff line number	Diff line change
`@@ -349,6 +349,7 @@ static int sfp_register_bus(struct sfp_bus *bus)`
`349`	`349`	`}`
`350`	`350`	`if (bus->started)`
`351`	`351`	`bus->socket_ops->start(bus->sfp);`
	`352`	`+ bus->netdev->sfp_bus = bus;`
`352`	`353`	`bus->registered = true;`
`353`	`354`	`return 0;`
`354`	`355`	`}`
`@@ -357,6 +358,7 @@ static void sfp_unregister_bus(struct sfp_bus *bus)`
`357`	`358`	`{`
`358`	`359`	`const struct sfp_upstream_ops *ops = bus->upstream_ops;`
`359`	`360`
	`361`	`+ bus->netdev->sfp_bus = NULL;`
`360`	`362`	`if (bus->registered) {`
`361`	`363`	`if (bus->started)`
`362`	`364`	`bus->socket_ops->stop(bus->sfp);`
`@@ -438,7 +440,6 @@ static void sfp_upstream_clear(struct sfp_bus *bus)`
`438`	`440`	`{`
`439`	`441`	`bus->upstream_ops = NULL;`
`440`	`442`	`bus->upstream = NULL;`
`441`		`- bus->netdev->sfp_bus = NULL;`
`442`	`443`	`bus->netdev = NULL;`
`443`	`444`	`}`
`444`	`445`
`@@ -467,7 +468,6 @@ struct sfp_bus sfp_register_upstream(struct fwnode_handle fwnode,`
`467`	`468`	`bus->upstream_ops = ops;`
`468`	`469`	`bus->upstream = upstream;`
`469`	`470`	`bus->netdev = ndev;`
`470`		`- ndev->sfp_bus = bus;`
`471`	`471`
`472`	`472`	`if (bus->sfp) {`
`473`	`473`	`ret = sfp_register_bus(bus);`