4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Paolo Abeni <pabeni@xxxxxxxxxx>
[ Upstream commit 058a6c033488494a6b1477b05fe8e1a16e344462 ]
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@xxxxxxxxxx>
Acked-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sched/cls_u32.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -496,6 +496,7 @@ static void u32_clear_hw_hnode(struct tc
static int u32_replace_hw_knode(struct tcf_proto *tp, struct tc_u_knode *n,
u32 flags)
{
+ struct tc_u_hnode *ht = rtnl_dereference(n->ht_down);
struct net_device *dev = tp->q->dev_queue->dev;
struct tc_cls_u32_offload u32_offload = {0};
struct tc_to_netdev offload;
@@ -520,7 +521,7 @@ static int u32_replace_hw_knode(struct t
offload.cls_u32->knode.sel = &n->sel;
offload.cls_u32->knode.exts = &n->exts;
if (n->ht_down)
- offload.cls_u32->knode.link_handle = n->ht_down->handle;
+ offload.cls_u32->knode.link_handle = ht->handle;
err = dev->netdev_ops->ndo_setup_tc(dev, tp->q->handle,
tp->protocol, &offload);
@@ -788,8 +789,9 @@ static void u32_replace_knode(struct tcf
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);
@@ -807,11 +809,11 @@ static struct tc_u_knode *u32_init_knode
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