From: Taehee Yoo ap420073@gmail.com
commit ae9b15fbe63447bc1d3bba3769f409d17ca6fdf6 upstream.
When the virtual interface's feature is updated, it synchronizes the updated feature for its own lower interface. This propagation logic should be worked as the iteration, not recursively. But it works recursively due to the netdev notification unexpectedly. This problem occurs when it disables LRO only for the team and bonding interface type.
team0 | +------+------+-----+-----+ | | | | | team1 team2 team3 ... team200
If team0's LRO feature is updated, it generates the NETDEV_FEAT_CHANGE event to its own lower interfaces(team1 ~ team200). It is worked by netdev_sync_lower_features(). So, the NETDEV_FEAT_CHANGE notification logic of each lower interface work iteratively. But generated NETDEV_FEAT_CHANGE event is also sent to the upper interface too. upper interface(team0) generates the NETDEV_FEAT_CHANGE event for its own lower interfaces again. lower and upper interfaces receive this event and generate this event again and again. So, the stack overflow occurs.
But it is not the infinite loop issue. Because the netdev_sync_lower_features() updates features before generating the NETDEV_FEAT_CHANGE event. Already synchronized lower interfaces skip notification logic. So, it is just the problem that iteration logic is changed to the recursive unexpectedly due to the notification mechanism.
Reproducer:
ip link add team0 type team ethtool -K team0 lro on for i in {1..200} do ip link add team$i master team0 type team ethtool -K team$i lro on done
ethtool -K team0 lro off
In order to fix it, the notifier_ctx member of bonding/team is introduced.
Reported-by: syzbot+60748c96cf5c6df8e581@syzkaller.appspotmail.com Fixes: fd867d51f889 ("net/core: generic support for disabling netdev features down stack") Signed-off-by: Taehee Yoo ap420073@gmail.com Reviewed-by: Eric Dumazet edumazet@google.com Reviewed-by: Nikolay Aleksandrov razor@blackwall.org Link: https://lore.kernel.org/r/20230517143010.3596250-1-ap420073@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/bonding/bond_main.c | 8 +++++++- drivers/net/team/team.c | 7 ++++++- include/linux/if_team.h | 1 + include/net/bonding.h | 1 + 4 files changed, 15 insertions(+), 2 deletions(-)
--- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -3537,7 +3537,11 @@ static int bond_slave_netdev_event(unsig unblock_netpoll_tx(); break; case NETDEV_FEAT_CHANGE: - bond_compute_features(bond); + if (!bond->notifier_ctx) { + bond->notifier_ctx = true; + bond_compute_features(bond); + bond->notifier_ctx = false; + } break; case NETDEV_RESEND_IGMP: /* Propagate to master device */ @@ -5360,6 +5364,8 @@ static int bond_init(struct net_device * if (!bond->wq) return -ENOMEM;
+ bond->notifier_ctx = false; + spin_lock_init(&bond->stats_lock); netdev_lockdep_set_classes(bond_dev);
--- a/drivers/net/team/team.c +++ b/drivers/net/team/team.c @@ -1624,6 +1624,7 @@ static int team_init(struct net_device *
team->dev = dev; team_set_no_mode(team); + team->notifier_ctx = false;
team->pcpu_stats = netdev_alloc_pcpu_stats(struct team_pcpu_stats); if (!team->pcpu_stats) @@ -3016,7 +3017,11 @@ static int team_device_event(struct noti team_del_slave(port->team->dev, dev); break; case NETDEV_FEAT_CHANGE: - team_compute_features(port->team); + if (!port->team->notifier_ctx) { + port->team->notifier_ctx = true; + team_compute_features(port->team); + port->team->notifier_ctx = false; + } break; case NETDEV_PRECHANGEMTU: /* Forbid to change mtu of underlaying device */ --- a/include/linux/if_team.h +++ b/include/linux/if_team.h @@ -208,6 +208,7 @@ struct team { bool queue_override_enabled; struct list_head *qom_lists; /* array of queue override mapping lists */ bool port_mtu_change_allowed; + bool notifier_ctx; struct { unsigned int count; unsigned int interval; /* in ms */ --- a/include/net/bonding.h +++ b/include/net/bonding.h @@ -216,6 +216,7 @@ struct bonding { struct bond_up_slave __rcu *usable_slaves; struct bond_up_slave __rcu *all_slaves; bool force_primary; + bool notifier_ctx; s32 slave_cnt; /* never change this value outside the attach/detach wrappers */ int (*recv_probe)(const struct sk_buff *, struct bonding *, struct slave *);