From: Luka Gejak During node merging, hsr_handle_sup_frame() walks node_curr->seq_blocks to update node_real without holding node_curr->seq_out_lock. This allows concurrent mutations from duplicate registration paths, risking inconsistent state or XArray/bitmap corruption. Fix this by locking both nodes' seq_out_lock during the merge. To prevent ABBA deadlocks, locks are acquired in order of memory address. Reviewed-by: Felix Maurer Fixes: 415e6367512b ("hsr: Implement more robust duplicate discard for PRP") Signed-off-by: Luka Gejak --- net/hsr/hsr_framereg.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-) diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c index 577fb588bc2f..d09875b33588 100644 --- a/net/hsr/hsr_framereg.c +++ b/net/hsr/hsr_framereg.c @@ -123,6 +123,40 @@ static void hsr_free_node_rcu(struct rcu_head *rn) hsr_free_node(node); } +static void hsr_lock_seq_out_pair(struct hsr_node *node_a, + struct hsr_node *node_b) +{ + if (node_a == node_b) { + spin_lock_bh(&node_a->seq_out_lock); + return; + } + + if (node_a < node_b) { + spin_lock_bh(&node_a->seq_out_lock); + spin_lock_nested(&node_b->seq_out_lock, SINGLE_DEPTH_NESTING); + } else { + spin_lock_bh(&node_b->seq_out_lock); + spin_lock_nested(&node_a->seq_out_lock, SINGLE_DEPTH_NESTING); + } +} + +static void hsr_unlock_seq_out_pair(struct hsr_node *node_a, + struct hsr_node *node_b) +{ + if (node_a == node_b) { + spin_unlock_bh(&node_a->seq_out_lock); + return; + } + + if (node_a < node_b) { + spin_unlock(&node_b->seq_out_lock); + spin_unlock_bh(&node_a->seq_out_lock); + } else { + spin_unlock(&node_a->seq_out_lock); + spin_unlock_bh(&node_b->seq_out_lock); + } +} + void hsr_del_nodes(struct list_head *node_db) { struct hsr_node *node; @@ -432,7 +466,7 @@ void hsr_handle_sup_frame(struct hsr_frame_info *frame) } ether_addr_copy(node_real->macaddress_B, ethhdr->h_source); - spin_lock_bh(&node_real->seq_out_lock); + hsr_lock_seq_out_pair(node_real, node_curr); for (i = 0; i < HSR_PT_PORTS; i++) { if (!node_curr->time_in_stale[i] && time_after(node_curr->time_in[i], node_real->time_in[i])) { @@ -455,7 +489,7 @@ void hsr_handle_sup_frame(struct hsr_frame_info *frame) src_blk->seq_nrs[i], HSR_SEQ_BLOCK_SIZE); } } - spin_unlock_bh(&node_real->seq_out_lock); + hsr_unlock_seq_out_pair(node_real, node_curr); node_real->addr_B_port = port_rcv->type; spin_lock_bh(&hsr->list_lock); -- 2.53.0