[ Upstream commit fe384e2fa36ca084a456fd30558cccc75b4b3fbd ]
callers of tcf_gact_goto_chain_index() can potentially read an old value of the chain index, or even dereference a NULL 'goto_chain' pointer, because 'goto_chain' and 'tcfa_action' are read in the traffic path without caring of concurrent write in the control path. The most recent value of chain index can be read also from a->tcfa_action (it's encoded there together with TC_ACT_GOTO_CHAIN bits), so we don't really need to dereference 'goto_chain': just read the chain id from the control action.
Fixes: e457d86ada27 ("net: sched: add couple of goto_chain helpers") Signed-off-by: Davide Caratti dcaratti@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin (Microsoft) sashal@kernel.org --- include/net/tc_act/tc_gact.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/net/tc_act/tc_gact.h b/include/net/tc_act/tc_gact.h index e82d93346b63..bb74ea83d57d 100644 --- a/include/net/tc_act/tc_gact.h +++ b/include/net/tc_act/tc_gact.h @@ -51,7 +51,7 @@ static inline bool is_tcf_gact_goto_chain(const struct tc_action *a)
static inline u32 tcf_gact_goto_chain_index(const struct tc_action *a) { - return a->goto_chain->index; + return READ_ONCE(a->tcfa_action) & TC_ACT_EXT_VAL_MASK; }
#endif /* __NET_TC_GACT_H */