Patch "sched: cls_flow: fix panic on filter replace" has been added to the 4.1-stable tree

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

sched: cls_flow: fix panic on filter replace

to the 4.1-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:
sched-cls_flow-fix-panic-on-filter-replace.patch
and it can be found in the queue-4.1 subdirectory.

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

From: Daniel Borkmann <[email protected]>
Date: Fri, 17 Jul 2015 22:38:45 +0200
Subject: sched: cls_flow: fix panic on filter replace

From: Daniel Borkmann <[email protected]>

[ Upstream commit 32b2f4b196b37695fdb42b31afcbc15399d6ef91 ]

The following test case causes a NULL pointer dereference in cls_flow:

tc filter add dev foo parent 1: handle 0x1 flow hash keys dst action ok tc filter replace dev foo parent 1: pref 49152 handle 0x1 \
flow hash keys mark action drop

To be more precise, actually two different panics are fixed, the first occurs because tcf_exts_init() is not called on the newly allocated filter when we do a replace. And the second panic uncovered after that happens since the arguments of list_replace_rcu() are swapped, the old element needs to be the first argument and the new element the second.

---
 net/sched/cls_flow.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

@@ -419,6 +419,8 @@ static int flow_change(struct net *net,
 	if (!fnew)
 		goto err2;
 
+	tcf_exts_init(&fnew->exts, TCA_FLOW_ACT, TCA_FLOW_POLICE);
+
 	fold = (struct flow_filter *)*arg;
 	if (fold) {
 		err = -EINVAL;

@@ -480,7 +482,6 @@ static int flow_change(struct net *net,
 		fnew->mask  = ~0U;
 		fnew->tp = tp;
 		get_random_bytes(&fnew->hashrnd, 4);
-		tcf_exts_init(&fnew->exts, TCA_FLOW_ACT, TCA_FLOW_POLICE);
 	}
 
 	fnew->perturb_timer.function = flow_perturbation;

@@ -520,7 +521,7 @@ static int flow_change(struct net *net,
 	if (*arg == 0)
 		list_add_tail_rcu(&fnew->list, &head->filters);
 	else
-		list_replace_rcu(&fnew->list, &fold->list);
+		list_replace_rcu(&fold->list, &fnew->list);
 
 	*arg = (unsigned long)fnew;
 

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

queue-4.1/sched-cls_bpf-fix-panic-on-filter-replace.patch queue-4.1/net-sched-fix-refcount-imbalance-in-actions.patch queue-4.1/sched-cls_flow-fix-panic-on-filter-replace.patch queue-4.1/act_bpf-fix-memory-leaks-when-replacing-bpf-programs.patch queue-4.1/packet-tpacket_snd-fix-signed-unsigned-comparison.patch queue-4.1/rtnetlink-verify-ifla_vf_info-attributes-before-passing-them-to-driver.patch queue-4.1/netlink-make-sure-ebusy-won-t-escape-from-netlink_insert.patch