[PATCH 3.14 11/96] team: fix possible null pointer dereference in team_handle_frame

From: Greg Kroah-Hartman
Date: Mon Mar 16 2015 - 11:16:46 EST

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


From: Jiri Pirko <jiri@xxxxxxxxxxx>

[ Upstream commit 57e595631904c827cfa1a0f7bbd7cc9a49da5745 ]

Currently following race is possible in team:

priv_flags &= ~IFF_TEAM_PORT
priv_flags & IFF_TEAM_PORT == 0
return NULL (instead of port got
from rx_handler_data)

The thing is that the flag is removed before rx_handler is unregistered.
If team_handle_frame is called in between, team_port_exists returns 0
and team_port_get_rcu will return NULL.
So do not check the flag here. It is guaranteed by netdev_rx_handler_unregister
that team_handle_frame will always see valid rx_handler_data pointer.

Signed-off-by: Jiri Pirko <jiri@xxxxxxxxxxx>
Fixes: 3d249d4ca7d0 ("net: introduce ethernet teaming device")
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/net/team/team.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -42,9 +42,7 @@

static struct team_port *team_port_get_rcu(const struct net_device *dev)
- struct team_port *port = rcu_dereference(dev->rx_handler_data);
- return team_port_exists(dev) ? port : NULL;
+ return rcu_dereference(dev->rx_handler_data);

static struct team_port *team_port_get_rtnl(const struct net_device *dev)

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