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Miller" , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, Kuniyuki Iwashima , Simon Horman , eric.dumazet@gmail.com, Eric Dumazet X-Patchwork-Delegate: kuba@kernel.org __skb_flow_dissect() can be called from arbitrary contexts. It must extend its rcu protection section to include the call to dev_net(), which can become dev_net_rcu(). This makes sure the net structure can not disappear under us. Fixes: 9b52e3f267a6 ("flow_dissector: handle no-skb use case")flow_dissect") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima --- net/core/flow_dissector.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 0e638a37aa0961de6281deeed227b3e7ef70e546..5db41bf2ed93e0df721c216ca4557dad16aa5f83 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -1108,10 +1108,12 @@ bool __skb_flow_dissect(const struct net *net, FLOW_DISSECTOR_KEY_BASIC, target_container); + rcu_read_lock(); + if (skb) { if (!net) { if (skb->dev) - net = dev_net(skb->dev); + net = dev_net_rcu(skb->dev); else if (skb->sk) net = sock_net(skb->sk); } @@ -1122,7 +1124,6 @@ bool __skb_flow_dissect(const struct net *net, enum netns_bpf_attach_type type = NETNS_BPF_FLOW_DISSECTOR; struct bpf_prog_array *run_array; - rcu_read_lock(); run_array = rcu_dereference(init_net.bpf.run_array[type]); if (!run_array) run_array = rcu_dereference(net->bpf.run_array[type]); @@ -1150,17 +1151,17 @@ bool __skb_flow_dissect(const struct net *net, prog = READ_ONCE(run_array->items[0].prog); result = bpf_flow_dissect(prog, &ctx, n_proto, nhoff, hlen, flags); - if (result == BPF_FLOW_DISSECTOR_CONTINUE) - goto dissect_continue; - __skb_flow_bpf_to_target(&flow_keys, flow_dissector, - target_container); - rcu_read_unlock(); - return result == BPF_OK; + if (result != BPF_FLOW_DISSECTOR_CONTINUE) { + __skb_flow_bpf_to_target(&flow_keys, flow_dissector, + target_container); + rcu_read_unlock(); + return result == BPF_OK; + } } -dissect_continue: - rcu_read_unlock(); } + rcu_read_unlock(); + if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ETH_ADDRS)) { struct ethhdr *eth = eth_hdr(skb);