From: Sebastian Andrzej Siewior bigeasy@linutronix.de
[ Upstream commit 0c74d9f79ec4299365bbe803baa736ae0068179e ]
Due to the hashed-MAC optimisation one problem become visible: hsr_handle_sup_frame() walks over the list of available nodes and merges two node entries into one if based on the information in the supervision both MAC addresses belong to one node. The list-walk happens on a RCU protected list and delete operation happens under a lock.
If the supervision arrives on both slave interfaces at the same time then this delete operation can occur simultaneously on two CPUs. The result is the first-CPU deletes the from the list and the second CPUs BUGs while attempting to dereference a poisoned list-entry. This happens more likely with the optimisation because a new node for the mac_B entry is created once a packet has been received and removed (merged) once the supervision frame has been received.
Avoid removing/ cleaning up a hsr_node twice by adding a `removed' field which is set to true after the removal and checked before the removal.
Fixes: f266a683a4804 ("net/hsr: Better frame dispatch") Signed-off-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/hsr/hsr_framereg.c | 16 +++++++++++----- net/hsr/hsr_framereg.h | 1 + 2 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c index e31949479305..440788e5b3e2 100644 --- a/net/hsr/hsr_framereg.c +++ b/net/hsr/hsr_framereg.c @@ -326,9 +326,12 @@ void hsr_handle_sup_frame(struct hsr_frame_info *frame) node_real->addr_B_port = port_rcv->type;
spin_lock_bh(&hsr->list_lock); - list_del_rcu(&node_curr->mac_list); + if (!node_curr->removed) { + list_del_rcu(&node_curr->mac_list); + node_curr->removed = true; + kfree_rcu(node_curr, rcu_head); + } spin_unlock_bh(&hsr->list_lock); - kfree_rcu(node_curr, rcu_head);
done: /* PRP uses v0 header */ @@ -502,9 +505,12 @@ void hsr_prune_nodes(struct timer_list *t) if (time_is_before_jiffies(timestamp + msecs_to_jiffies(HSR_NODE_FORGET_TIME))) { hsr_nl_nodedown(hsr, node->macaddress_A); - list_del_rcu(&node->mac_list); - /* Note that we need to free this entry later: */ - kfree_rcu(node, rcu_head); + if (!node->removed) { + list_del_rcu(&node->mac_list); + node->removed = true; + /* Note that we need to free this entry later: */ + kfree_rcu(node, rcu_head); + } } } spin_unlock_bh(&hsr->list_lock); diff --git a/net/hsr/hsr_framereg.h b/net/hsr/hsr_framereg.h index d9628e7a5f05..f9c83dc02ca5 100644 --- a/net/hsr/hsr_framereg.h +++ b/net/hsr/hsr_framereg.h @@ -80,6 +80,7 @@ struct hsr_node { bool san_a; bool san_b; u16 seq_out[HSR_PT_PORTS]; + bool removed; struct rcu_head rcu_head; };