This is a note to let you know that I've just added the patch titled bonding: fix suspicious RCU usage in bond_ipsec_offload_ok() to the 5.13-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: bonding-fix-suspicious-rcu-usage-in-bond_ipsec_offlo.patch and it can be found in the queue-5.13 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit d7145013c4c46dcaf9fe414cafd3f531dbfa7166 Author: Taehee Yoo <ap420073@xxxxxxxxx> Date: Mon Jul 5 15:38:13 2021 +0000 bonding: fix suspicious RCU usage in bond_ipsec_offload_ok() [ Upstream commit 955b785ec6b3b2f9b91914d6eeac8ee66ee29239 ] To dereference bond->curr_active_slave, it uses rcu_dereference(). But it and the caller doesn't acquire RCU so a warning occurs. So add rcu_read_lock(). Splat looks like: WARNING: suspicious RCU usage 5.13.0-rc6+ #1179 Not tainted drivers/net/bonding/bond_main.c:571 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by ping/974: #0: ffff888109e7db70 (sk_lock-AF_INET){+.+.}-{0:0}, at: raw_sendmsg+0x1303/0x2cb0 stack backtrace: CPU: 2 PID: 974 Comm: ping Not tainted 5.13.0-rc6+ #1179 Call Trace: dump_stack+0xa4/0xe5 bond_ipsec_offload_ok+0x1f4/0x260 [bonding] xfrm_output+0x179/0x890 xfrm4_output+0xfa/0x410 ? __xfrm4_output+0x4b0/0x4b0 ? __ip_make_skb+0xecc/0x2030 ? xfrm4_udp_encap_rcv+0x800/0x800 ? ip_local_out+0x21/0x3a0 ip_send_skb+0x37/0xa0 raw_sendmsg+0x1bfd/0x2cb0 Fixes: 18cb261afd7b ("bonding: support hardware encryption offload to slaves") Signed-off-by: Taehee Yoo <ap420073@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 3f67b4b794ac..d267791a06c0 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -573,24 +573,34 @@ static bool bond_ipsec_offload_ok(struct sk_buff *skb, struct xfrm_state *xs) struct net_device *real_dev; struct slave *curr_active; struct bonding *bond; + int err; bond = netdev_priv(bond_dev); + rcu_read_lock(); curr_active = rcu_dereference(bond->curr_active_slave); real_dev = curr_active->dev; - if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) - return true; + if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) { + err = true; + goto out; + } - if (!xs->xso.real_dev) - return false; + if (!xs->xso.real_dev) { + err = false; + goto out; + } if (!real_dev->xfrmdev_ops || !real_dev->xfrmdev_ops->xdo_dev_offload_ok || netif_is_bond_master(real_dev)) { - return false; + err = false; + goto out; } - return real_dev->xfrmdev_ops->xdo_dev_offload_ok(skb, xs); + err = real_dev->xfrmdev_ops->xdo_dev_offload_ok(skb, xs); +out: + rcu_read_unlock(); + return err; } static const struct xfrmdev_ops bond_xfrmdev_ops = {