cls_u32: add missing RCU annotation.

In a couple of points of the control path, n->ht_down is currently
accessed without the required RCU annotation. The accesses are
safe, but sparse complaints. Since we already held the
rtnl lock, let use rtnl_dereference().

Fixes: a1b7c5fd7fe9 ("net: sched: add cls_u32 offload hooks for netdevs")
Fixes: de5df63228fc ("net: sched: cls_u32 changes to knode must appear atomic to readers")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 5 deletions

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index 60c892c36a60..e3c5e390ec23 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -548,6 +548,7 @@ static void u32_remove_hw_knode(struct tcf_proto *tp, struct tc_u_knode *n,
 static int u32_replace_hw_knode(struct tcf_proto *tp, struct tc_u_knode *n,
                                 u32 flags, struct netlink_ext_ack *extack)
 {
+        struct tc_u_hnode *ht = rtnl_dereference(n->ht_down);
         struct tcf_block *block = tp->chain->block;
         struct tc_cls_u32_offload cls_u32 = {};
         bool skip_sw = tc_skip_sw(flags);
@@ -567,7 +568,7 @@ static int u32_replace_hw_knode(struct tcf_proto *tp, struct tc_u_knode *n,
         cls_u32.knode.sel = &n->sel;
         cls_u32.knode.exts = &n->exts;
         if (n->ht_down)
-                cls_u32.knode.link_handle = n->ht_down->handle;
+                cls_u32.knode.link_handle = ht->handle;
 
         err = tc_setup_cb_call(block, NULL, TC_SETUP_CLSU32, &cls_u32, skip_sw);
         if (err < 0) {
@@ -855,8 +856,9 @@ static void u32_replace_knode(struct tcf_proto *tp, struct tc_u_common *tp_c,
 static struct tc_u_knode *u32_init_knode(struct tcf_proto *tp,
                                          struct tc_u_knode *n)
 {
-        struct tc_u_knode *new;
+        struct tc_u_hnode *ht = rtnl_dereference(n->ht_down);
         struct tc_u32_sel *s = &n->sel;
+        struct tc_u_knode *new;
 
         new = kzalloc(sizeof(*n) + s->nkeys*sizeof(struct tc_u32_key),
                       GFP_KERNEL);
@@ -874,11 +876,11 @@ static struct tc_u_knode *u32_init_knode(struct tcf_proto *tp,
         new->fshift = n->fshift;
         new->res = n->res;
         new->flags = n->flags;
-        RCU_INIT_POINTER(new->ht_down, n->ht_down);
+        RCU_INIT_POINTER(new->ht_down, ht);
 
         /* bump reference count as long as we hold pointer to structure */
-        if (new->ht_down)
-                new->ht_down->refcnt++;
+        if (ht)
+                ht->refcnt++;
 
 #ifdef CONFIG_CLS_U32_PERF
         /* Statistics may be incremented by readers during update