From: Ido Schimmel <idosch@mellanox.com>
Date: Thu, 19 Mar 2020 13:33:10 +0200
Subject: net: sched: Do not assume RTNL is held in tunnel key action helpers
Patch-mainline: v5.7-rc1
Git-commit: 3ebaf6da07168c3ab80dac71e063a9ae5a6882ff
References: jsc#SLE-15075
The cited commit removed RTNL from tc_setup_flow_action(), but the
function calls two tunnel key action helpers that use rtnl_dereference()
to fetch the action's parameters. This leads to "suspicious RCU usage"
warnings [1][2].
Change the helpers to use rcu_dereference_protected() while requiring
the action's lock to be held. This is safe because the two helpers are
only called from tc_setup_flow_action() which acquires the lock.
[1]
[ 156.950855] =============================
[ 156.955463] WARNING: suspicious RCU usage
[ 156.960085] 5.6.0-rc5-custom-47426-gdfe43878d573 #2409 Not tainted
[ 156.967116] -----------------------------
[ 156.971728] include/net/tc_act/tc_tunnel_key.h:31 suspicious rcu_dereference_protected() usage!
[ 156.981583]
[ 156.981583] other info that might help us debug this:
[ 156.981583]
[ 156.990675]
[ 156.990675] rcu_scheduler_active = 2, debug_locks = 1
[ 156.998205] 1 lock held by tc/877:
[ 157.002187] #0: ffff8881cbf7bea0 (&(&p->tcfa_lock)->rlock){+...}, at: tc_setup_flow_action+0xbe/0x4f78
[ 157.012866]
[ 157.012866] stack backtrace:
[ 157.017886] CPU: 2 PID: 877 Comm: tc Not tainted 5.6.0-rc5-custom-47426-gdfe43878d573 #2409
[ 157.027253] Hardware name: Mellanox Technologies Ltd. MSN2100-CB2FO/SA001017, BIOS 5.6.5 06/07/2016
[ 157.037389] Call Trace:
[ 157.040170] dump_stack+0xfd/0x178
[ 157.044034] lockdep_rcu_suspicious+0x14a/0x153
[ 157.049157] tc_setup_flow_action+0x89f/0x4f78
[ 157.054227] fl_hw_replace_filter+0x375/0x640
[ 157.064348] fl_change+0x28ec/0x4f6b
[ 157.088843] tc_new_tfilter+0x15e2/0x2260
[ 157.176801] rtnetlink_rcv_msg+0x8d6/0xb60
[ 157.190915] netlink_rcv_skb+0x177/0x460
[ 157.208884] rtnetlink_rcv+0x21/0x30
[ 157.212925] netlink_unicast+0x5d0/0x7f0
[ 157.227728] netlink_sendmsg+0x981/0xe90
[ 157.245416] ____sys_sendmsg+0x76d/0x8f0
[ 157.255348] ___sys_sendmsg+0x10f/0x190
[ 157.320308] __sys_sendmsg+0x115/0x1f0
[ 157.342553] __x64_sys_sendmsg+0x7d/0xc0
[ 157.346987] do_syscall_64+0xc1/0x600
[ 157.351142] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[2]
[ 157.432346] =============================
[ 157.436937] WARNING: suspicious RCU usage
[ 157.441537] 5.6.0-rc5-custom-47426-gdfe43878d573 #2409 Not tainted
[ 157.448559] -----------------------------
[ 157.453204] include/net/tc_act/tc_tunnel_key.h:43 suspicious rcu_dereference_protected() usage!
[ 157.463042]
[ 157.463042] other info that might help us debug this:
[ 157.463042]
[ 157.472112]
[ 157.472112] rcu_scheduler_active = 2, debug_locks = 1
[ 157.479529] 1 lock held by tc/877:
[ 157.483442] #0: ffff8881cbf7bea0 (&(&p->tcfa_lock)->rlock){+...}, at: tc_setup_flow_action+0xbe/0x4f78
[ 157.494119]
[ 157.494119] stack backtrace:
[ 157.499114] CPU: 2 PID: 877 Comm: tc Not tainted 5.6.0-rc5-custom-47426-gdfe43878d573 #2409
[ 157.508485] Hardware name: Mellanox Technologies Ltd. MSN2100-CB2FO/SA001017, BIOS 5.6.5 06/07/2016
[ 157.518628] Call Trace:
[ 157.521416] dump_stack+0xfd/0x178
[ 157.525293] lockdep_rcu_suspicious+0x14a/0x153
[ 157.530425] tc_setup_flow_action+0x993/0x4f78
[ 157.535505] fl_hw_replace_filter+0x375/0x640
[ 157.545650] fl_change+0x28ec/0x4f6b
[ 157.570204] tc_new_tfilter+0x15e2/0x2260
[ 157.658199] rtnetlink_rcv_msg+0x8d6/0xb60
[ 157.672315] netlink_rcv_skb+0x177/0x460
[ 157.690278] rtnetlink_rcv+0x21/0x30
[ 157.694320] netlink_unicast+0x5d0/0x7f0
[ 157.709129] netlink_sendmsg+0x981/0xe90
[ 157.726813] ____sys_sendmsg+0x76d/0x8f0
[ 157.736725] ___sys_sendmsg+0x10f/0x190
[ 157.801721] __sys_sendmsg+0x115/0x1f0
[ 157.823967] __x64_sys_sendmsg+0x7d/0xc0
[ 157.828403] do_syscall_64+0xc1/0x600
[ 157.832558] entry_SYSCALL_64_after_hwframe+0x49/0xbe
Fixes: b15e7a6e8d31 ("net: sched: don't take rtnl lock during flow_action setup")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
include/net/tc_act/tc_tunnel_key.h | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/include/net/tc_act/tc_tunnel_key.h
+++ b/include/net/tc_act/tc_tunnel_key.h
@@ -28,8 +28,10 @@ static inline bool is_tcf_tunnel_set(con
{
#ifdef CONFIG_NET_CLS_ACT
struct tcf_tunnel_key *t = to_tunnel_key(a);
- struct tcf_tunnel_key_params *params = rtnl_dereference(t->params);
+ struct tcf_tunnel_key_params *params;
+ params = rcu_dereference_protected(t->params,
+ lockdep_is_held(&a->tcfa_lock));
if (a->ops && a->ops->id == TCA_ID_TUNNEL_KEY)
return params->tcft_action == TCA_TUNNEL_KEY_ACT_SET;
#endif
@@ -40,8 +42,10 @@ static inline bool is_tcf_tunnel_release
{
#ifdef CONFIG_NET_CLS_ACT
struct tcf_tunnel_key *t = to_tunnel_key(a);
- struct tcf_tunnel_key_params *params = rtnl_dereference(t->params);
+ struct tcf_tunnel_key_params *params;
+ params = rcu_dereference_protected(t->params,
+ lockdep_is_held(&a->tcfa_lock));
if (a->ops && a->ops->id == TCA_ID_TUNNEL_KEY)
return params->tcft_action == TCA_TUNNEL_KEY_ACT_RELEASE;
#endif