Messages in this thread Patch in this message | | | From | Jason Wang <> | Subject | [PATCH net-next] tuntap: fix possible deadlock when fail to register netdev | Date | Fri, 8 Dec 2017 10:54:15 +0800 |
| |
Private destructor could be called when register_netdev() fail with rtnl lock held. This will lead deadlock in tun_free_netdev() who tries to hold rtnl_lock. Fixing this by switching to use spinlock to synchronize.
Fixes: 96f84061620c ("tun: add eBPF based queue selection method") Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Willem de Bruijn <willemb@google.com> Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/net/tun.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 787cc35..f7ccd79 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -2050,8 +2050,11 @@ static int __tun_set_steering_ebpf(struct tun_struct *tun, new->prog = prog; } - old = rtnl_dereference(tun->steering_prog); + spin_lock(&tun->lock); + old = rcu_dereference_protected(tun->steering_prog, + lock_is_held(&tun->lock)); rcu_assign_pointer(tun->steering_prog, new); + spin_unlock(&tun->lock); if (old) call_rcu(&old->rcu, tun_steering_prog_free); @@ -2067,9 +2070,7 @@ static void tun_free_netdev(struct net_device *dev) free_percpu(tun->pcpu_stats); tun_flow_uninit(tun); security_tun_dev_free_security(tun->security); - rtnl_lock(); __tun_set_steering_ebpf(tun, NULL); - rtnl_unlock(); } static void tun_setup(struct net_device *dev) -- 2.7.4
| |