This is a note to let you know that I've just added the patch titled openvswitch: Zero flows on allocation. to the 4.2-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: openvswitch-zero-flows-on-allocation.patch and it can be found in the queue-4.2 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Wed Sep 30 05:25:07 CEST 2015 From: Jesse Gross <jesse@xxxxxxxxxx> Date: Mon, 21 Sep 2015 20:21:20 -0700 Subject: openvswitch: Zero flows on allocation. From: Jesse Gross <jesse@xxxxxxxxxx> [ Upstream commit ae5f2fb1d51fa128a460bcfbe3c56d7ab8bf6a43 ] When support for megaflows was introduced, OVS needed to start installing flows with a mask applied to them. Since masking is an expensive operation, OVS also had an optimization that would only take the parts of the flow keys that were covered by a non-zero mask. The values stored in the remaining pieces should not matter because they are masked out. While this works fine for the purposes of matching (which must always look at the mask), serialization to netlink can be problematic. Since the flow and the mask are serialized separately, the uninitialized portions of the flow can be encoded with whatever values happen to be present. In terms of functionality, this has little effect since these fields will be masked out by definition. However, it leaks kernel memory to userspace, which is a potential security vulnerability. It is also possible that other code paths could look at the masked key and get uninitialized data, although this does not currently appear to be an issue in practice. This removes the mask optimization for flows that are being installed. This was always intended to be the case as the mask optimizations were really targetting per-packet flow operations. Fixes: 03f0d916 ("openvswitch: Mega flow implementation") Signed-off-by: Jesse Gross <jesse@xxxxxxxxxx> Acked-by: Pravin B Shelar <pshelar@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/openvswitch/datapath.c | 4 ++-- net/openvswitch/flow_table.c | 23 ++++++++++++----------- net/openvswitch/flow_table.h | 2 +- 3 files changed, 15 insertions(+), 14 deletions(-) --- a/net/openvswitch/datapath.c +++ b/net/openvswitch/datapath.c @@ -920,7 +920,7 @@ static int ovs_flow_cmd_new(struct sk_bu if (error) goto err_kfree_flow; - ovs_flow_mask_key(&new_flow->key, &key, &mask); + ovs_flow_mask_key(&new_flow->key, &key, true, &mask); /* Extract flow identifier. */ error = ovs_nla_get_identifier(&new_flow->id, a[OVS_FLOW_ATTR_UFID], @@ -1047,7 +1047,7 @@ static struct sw_flow_actions *get_flow_ struct sw_flow_key masked_key; int error; - ovs_flow_mask_key(&masked_key, key, mask); + ovs_flow_mask_key(&masked_key, key, true, mask); error = ovs_nla_copy_actions(a, &masked_key, &acts, log); if (error) { OVS_NLERR(log, --- a/net/openvswitch/flow_table.c +++ b/net/openvswitch/flow_table.c @@ -56,20 +56,21 @@ static u16 range_n_bytes(const struct sw } void ovs_flow_mask_key(struct sw_flow_key *dst, const struct sw_flow_key *src, - const struct sw_flow_mask *mask) + bool full, const struct sw_flow_mask *mask) { - const long *m = (const long *)((const u8 *)&mask->key + - mask->range.start); - const long *s = (const long *)((const u8 *)src + - mask->range.start); - long *d = (long *)((u8 *)dst + mask->range.start); + int start = full ? 0 : mask->range.start; + int len = full ? sizeof *dst : range_n_bytes(&mask->range); + const long *m = (const long *)((const u8 *)&mask->key + start); + const long *s = (const long *)((const u8 *)src + start); + long *d = (long *)((u8 *)dst + start); int i; - /* The memory outside of the 'mask->range' are not set since - * further operations on 'dst' only uses contents within - * 'mask->range'. + /* If 'full' is true then all of 'dst' is fully initialized. Otherwise, + * if 'full' is false the memory outside of the 'mask->range' is left + * uninitialized. This can be used as an optimization when further + * operations on 'dst' only use contents within 'mask->range'. */ - for (i = 0; i < range_n_bytes(&mask->range); i += sizeof(long)) + for (i = 0; i < len; i += sizeof(long)) *d++ = *s++ & *m++; } @@ -473,7 +474,7 @@ static struct sw_flow *masked_flow_looku u32 hash; struct sw_flow_key masked_key; - ovs_flow_mask_key(&masked_key, unmasked, mask); + ovs_flow_mask_key(&masked_key, unmasked, false, mask); hash = flow_hash(&masked_key, &mask->range); head = find_bucket(ti, hash); hlist_for_each_entry_rcu(flow, head, flow_table.node[ti->node_ver]) { --- a/net/openvswitch/flow_table.h +++ b/net/openvswitch/flow_table.h @@ -86,5 +86,5 @@ struct sw_flow *ovs_flow_tbl_lookup_ufid bool ovs_flow_cmp(const struct sw_flow *, const struct sw_flow_match *); void ovs_flow_mask_key(struct sw_flow_key *dst, const struct sw_flow_key *src, - const struct sw_flow_mask *mask); + bool full, const struct sw_flow_mask *mask); #endif /* flow_table.h */ Patches currently in stable-queue which might be from jesse@xxxxxxxxxx are queue-4.2/openvswitch-zero-flows-on-allocation.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html