Patch "cls_u32: add missing RCU annotation." has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Feb 6, 2018

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Networking Stable branch Traffic control (tc)

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2018-02-06 20:48 UTC #0 lore raw

This is a note to let you know that I've just added the patch titled

cls_u32: add missing RCU annotation.

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
cls_u32-add-missing-rcu-annotation.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From foo@baz Tue Feb 6 12:42:23 PST 2018

From: Paolo Abeni <[email protected]>
Date: Fri, 2 Feb 2018 16:02:22 +0100
Subject: cls_u32: add missing RCU annotation.

From: Paolo Abeni <[email protected]>

[ 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 <[email protected]>

Acked-by Cong Wang <[email protected]>

Signed-off-by David S. Miller <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 net/sched/cls_u32.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

net/sched/cls_u32.c +7 -5

@@ -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

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/cls_u32-add-missing-rcu-annotation.patch