| From | lizf@kernel ... | Subject | [PATCH 3.4 052/172] team: fix possible null pointer dereference in team_handle_frame | Date | Tue, 16 Jun 2015 16:35:06 +0800 |
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From: Jiri Pirko <jiri@resnulli.us>
3.4.108-rc1 review patch. If anyone has any objections, please let me know.
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commit 57e595631904c827cfa1a0f7bbd7cc9a49da5745 upstream.
Currently following race is possible in team:
CPU0 CPU1 team_port_del team_upper_dev_unlink priv_flags &= ~IFF_TEAM_PORT team_handle_frame team_port_get_rcu team_port_exists priv_flags & IFF_TEAM_PORT == 0 return NULL (instead of port got from rx_handler_data) netdev_rx_handler_unregister
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@resnulli.us> Fixes: 3d249d4ca7d0 ("net: introduce ethernet teaming device") Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Zefan Li <lizefan@huawei.com> --- drivers/net/team/team.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c index d16800f..56299e9 100644 --- a/drivers/net/team/team.c +++ b/drivers/net/team/team.c @@ -39,9 +39,7 @@ 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) -- 1.9.1
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