From: Jamal Hadi Salim <jhs@mojatatu.com> mainline inclusion from mainline-v7.2-rc3 commit 6301f6a34ed86fe6f3b7b3211ea069f3677fc559 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/17369 CVE: CVE-2026-72390 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- This is a followup based on sashiko comments [1] on commit e5b811fe7931 ("net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF") Use plain rcu_read_lock()/spin_lock() in teql_master_xmit() instead of the _bh variants, since ndo_start_xmit is already invoked with BH disabled by the core stack and the _bh primitives can warn in_hardirq() when xmit is reached through netpoll or a softirq xmit path with hard IRQs disabled. Moves rcu_read_lock() after restart: label + adds rcu_read_unlock() before goto restart (fixes the unbounded RCU hold across retries) [1] https://sashiko.dev/#/patchset/20260628111229.669751-1-jhs%40mojatatu.com Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com> Fixes: e5b811fe7931 ("net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF") Link: https://patch.msgid.link/20260630150922.238714-1-jhs@mojatatu.com Signed-off-by: Paolo Abeni <pabeni@redhat.com> Conflicts: net/sched/sch_teql.c [surrounding context in teql_master_xmit() shifted after e5b811fe7931] Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/sched/sch_teql.c | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-) diff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c index 1b58779e5d99..bb77e519408f 100644 --- a/net/sched/sch_teql.c +++ b/net/sched/sch_teql.c @@ -311,14 +311,14 @@ static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev) int subq = skb_get_queue_mapping(skb); struct sk_buff *skb_res = NULL; - rcu_read_lock_bh(); - - start = rcu_dereference_bh(master->slaves); - restart: nores = 0; busy = 0; + rcu_read_lock(); + + start = rcu_dereference(master->slaves); + q = start; if (!q) goto drop; @@ -344,17 +344,17 @@ static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev) netdev_start_xmit(skb, slave, slave_txq, false) == NETDEV_TX_OK) { __netif_tx_unlock(slave_txq); - spin_lock_bh(&master->slaves_lock); + spin_lock(&master->slaves_lock); if (rcu_dereference_protected(master->slaves, lockdep_is_held(&master->slaves_lock)) == q) rcu_assign_pointer(master->slaves, rcu_dereference_protected(NEXT_SLAVE(q), lockdep_is_held(&master->slaves_lock))); - spin_unlock_bh(&master->slaves_lock); + spin_unlock(&master->slaves_lock); netif_wake_queue(dev); master->tx_packets++; master->tx_bytes += length; - rcu_read_unlock_bh(); + rcu_read_unlock(); return NETDEV_TX_OK; } __netif_tx_unlock(slave_txq); @@ -363,37 +363,38 @@ static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev) busy = 1; break; case 1: - spin_lock_bh(&master->slaves_lock); + spin_lock(&master->slaves_lock); if (rcu_dereference_protected(master->slaves, lockdep_is_held(&master->slaves_lock)) == q) rcu_assign_pointer(master->slaves, rcu_dereference_protected(NEXT_SLAVE(q), lockdep_is_held(&master->slaves_lock))); - spin_unlock_bh(&master->slaves_lock); - rcu_read_unlock_bh(); + spin_unlock(&master->slaves_lock); + rcu_read_unlock(); return NETDEV_TX_OK; default: nores = 1; break; } __skb_pull(skb, skb_network_offset(skb)); - } while ((q = rcu_dereference_bh(NEXT_SLAVE(q))) != start); + } while ((q = rcu_dereference(NEXT_SLAVE(q))) != start); if (nores && skb_res == NULL) { skb_res = skb; + rcu_read_unlock(); goto restart; } if (busy) { netif_stop_queue(dev); - rcu_read_unlock_bh(); + rcu_read_unlock(); return NETDEV_TX_BUSY; } master->tx_errors++; drop: master->tx_dropped++; - rcu_read_unlock_bh(); + rcu_read_unlock(); dev_kfree_skb(skb); return NETDEV_TX_OK; } -- 2.43.0