path: root/include/net/act_api.h
diff options
authorDavide Caratti <dcaratti@redhat.com>2019-03-20 15:00:16 +0100
committerDavid S. Miller <davem@davemloft.net>2019-03-21 13:26:42 -0700
commitee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 (patch)
tree33700fcef44dffdc033bf13c90604e426e4fc47d /include/net/act_api.h
parentnet/sched: don't dereference a->goto_chain to read the chain index (diff)
net/sched: let actions use RCU to access 'goto_chain'
use RCU when accessing the action chain, to avoid use after free in the traffic path when 'goto chain' is replaced on existing TC actions (see script below). Since the control action is read in the traffic path without holding the action spinlock, we need to explicitly ensure that a->goto_chain is not NULL before dereferencing (i.e it's not sufficient to rely on the value of TC_ACT_GOTO_CHAIN bits). Not doing so caused NULL dereferences in tcf_action_goto_chain_exec() when the following script: # tc chain add dev dd0 chain 42 ingress protocol ip flower \ > ip_proto udp action pass index 4 # tc filter add dev dd0 ingress protocol ip flower \ > ip_proto udp action csum udp goto chain 42 index 66 # tc chain del dev dd0 chain 42 ingress (start UDP traffic towards dd0) # tc action replace action csum udp pass index 66 was run repeatedly for several hours. Suggested-by: Cong Wang <xiyou.wangcong@gmail.com> Suggested-by: Vlad Buslov <vladbu@mellanox.com> Signed-off-by: Davide Caratti <dcaratti@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/act_api.h')
1 files changed, 1 insertions, 1 deletions
diff --git a/include/net/act_api.h b/include/net/act_api.h
index 54fbb49bd08a..c61a1bf4e3de 100644
--- a/include/net/act_api.h
+++ b/include/net/act_api.h
@@ -39,7 +39,7 @@ struct tc_action {
struct gnet_stats_basic_cpu __percpu *cpu_bstats_hw;
struct gnet_stats_queue __percpu *cpu_qstats;
struct tc_cookie __rcu *act_cookie;
- struct tcf_chain *goto_chain;
+ struct tcf_chain __rcu *goto_chain;
#define tcf_index common.tcfa_index
#define tcf_refcnt common.tcfa_refcnt