From: Jakub Kicinski <kuba@kernel.org> mainline inclusion from mainline-v6.8-rc6 commit 52f671db18823089a02f07efc04efdb2272ddc17 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9E2LT CVE: CVE-2024-26740 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- The test Davide added in commit ca22da2fbd69 ("act_mirred: use the backlog for nested calls to mirred ingress") hangs our testing VMs every 10 or so runs, with the familiar tcp_v4_rcv -> tcp_v4_rcv deadlock reported by lockdep. The problem as previously described by Davide (see Link) is that if we reverse flow of traffic with the redirect (egress -> ingress) we may reach the same socket which generated the packet. And we may still be holding its socket lock. The common solution to such deadlocks is to put the packet in the Rx backlog, rather than run the Rx path inline. Do that for all egress -> ingress reversals, not just once we started to nest mirred calls. In the past there was a concern that the backlog indirection will lead to loss of error reporting / less accurate stats. But the current workaround does not seem to address the issue. Fixes: 53592b364001 ("net/sched: act_mirred: Implement ingress actions") Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Suggested-by: Davide Caratti <dcaratti@redhat.com> Link: https://lore.kernel.org/netdev/33dc43f587ec1388ba456b4915c75f02a8aae226.1663... Signed-off-by: Jakub Kicinski <kuba@kernel.org> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net> Conflicts: net/sched/act_mirred.c Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> --- net/sched/act_mirred.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c index febf06b8bbdf..336db2c938b5 100644 --- a/net/sched/act_mirred.c +++ b/net/sched/act_mirred.c @@ -197,18 +197,14 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla, return ret; } -static bool is_mirred_nested(void) -{ - return unlikely(__this_cpu_read(mirred_rec_level) > 1); -} - -static int tcf_mirred_forward(bool want_ingress, struct sk_buff *skb) +static int +tcf_mirred_forward(bool at_ingress, bool want_ingress, struct sk_buff *skb) { int err; if (!want_ingress) err = dev_queue_xmit(skb); - else if (is_mirred_nested()) + else if (!at_ingress) err = netif_rx(skb); else err = netif_receive_skb(skb); @@ -300,14 +296,15 @@ static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a, if (use_reinsert) { res->ingress = want_ingress; res->qstats = this_cpu_ptr(m->common.cpu_qstats); - if (tcf_mirred_forward(want_ingress, skb) && res->qstats) + if (tcf_mirred_forward(skb_at_tc_ingress(skb), want_ingress, skb) + && res->qstats) qstats_overlimit_inc(res->qstats); __this_cpu_dec(mirred_rec_level); return TC_ACT_CONSUMED; } } - err = tcf_mirred_forward(want_ingress, skb2); + err = tcf_mirred_forward(skb_at_tc_ingress(skb), want_ingress, skb2); if (err) { out: qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats)); -- 2.34.1