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Subject[Linux-kernel-mentees] [PATCH net] openvswitch: Prevent kernel-infoleak in ovs_ct_put_key()
Date
ovs_ct_put_key() is potentially copying uninitialized kernel stack memory
into socket buffers, since the compiler may leave a 3-byte hole at the end
of `struct ovs_key_ct_tuple_ipv4` and `struct ovs_key_ct_tuple_ipv6`. Fix
it by initializing `orig` with memset().

Cc: stable@vger.kernel.org
Fixes: 9dd7f8907c37 ("openvswitch: Add original direction conntrack tuple to sw_flow_key.")
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
---
Reference: https://lwn.net/Articles/417989/

$ pahole -C "ovs_key_ct_tuple_ipv4" net/openvswitch/conntrack.o
struct ovs_key_ct_tuple_ipv4 {
__be32 ipv4_src; /* 0 4 */
__be32 ipv4_dst; /* 4 4 */
__be16 src_port; /* 8 2 */
__be16 dst_port; /* 10 2 */
__u8 ipv4_proto; /* 12 1 */

/* size: 16, cachelines: 1, members: 5 */
/* padding: 3 */
/* last cacheline: 16 bytes */
};
$ pahole -C "ovs_key_ct_tuple_ipv6" net/openvswitch/conntrack.o
struct ovs_key_ct_tuple_ipv6 {
__be32 ipv6_src[4]; /* 0 16 */
__be32 ipv6_dst[4]; /* 16 16 */
__be16 src_port; /* 32 2 */
__be16 dst_port; /* 34 2 */
__u8 ipv6_proto; /* 36 1 */

/* size: 40, cachelines: 1, members: 5 */
/* padding: 3 */
/* last cacheline: 40 bytes */
};

net/openvswitch/conntrack.c | 38 +++++++++++++++++++------------------
1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index 4340f25fe390..98d393e70de3 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -276,10 +276,6 @@ void ovs_ct_fill_key(const struct sk_buff *skb, struct sw_flow_key *key)
ovs_ct_update_key(skb, NULL, key, false, false);
}

-#define IN6_ADDR_INITIALIZER(ADDR) \
- { (ADDR).s6_addr32[0], (ADDR).s6_addr32[1], \
- (ADDR).s6_addr32[2], (ADDR).s6_addr32[3] }
-
int ovs_ct_put_key(const struct sw_flow_key *swkey,
const struct sw_flow_key *output, struct sk_buff *skb)
{
@@ -301,24 +297,30 @@ int ovs_ct_put_key(const struct sw_flow_key *swkey,

if (swkey->ct_orig_proto) {
if (swkey->eth.type == htons(ETH_P_IP)) {
- struct ovs_key_ct_tuple_ipv4 orig = {
- output->ipv4.ct_orig.src,
- output->ipv4.ct_orig.dst,
- output->ct.orig_tp.src,
- output->ct.orig_tp.dst,
- output->ct_orig_proto,
- };
+ struct ovs_key_ct_tuple_ipv4 orig;
+
+ memset(&orig, 0, sizeof(orig));
+ orig.ipv4_src = output->ipv4.ct_orig.src;
+ orig.ipv4_dst = output->ipv4.ct_orig.dst;
+ orig.src_port = output->ct.orig_tp.src;
+ orig.dst_port = output->ct.orig_tp.dst;
+ orig.ipv4_proto = output->ct_orig_proto;
+
if (nla_put(skb, OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV4,
sizeof(orig), &orig))
return -EMSGSIZE;
} else if (swkey->eth.type == htons(ETH_P_IPV6)) {
- struct ovs_key_ct_tuple_ipv6 orig = {
- IN6_ADDR_INITIALIZER(output->ipv6.ct_orig.src),
- IN6_ADDR_INITIALIZER(output->ipv6.ct_orig.dst),
- output->ct.orig_tp.src,
- output->ct.orig_tp.dst,
- output->ct_orig_proto,
- };
+ struct ovs_key_ct_tuple_ipv6 orig;
+
+ memset(&orig, 0, sizeof(orig));
+ memcpy(orig.ipv6_src, output->ipv6.ct_orig.src.s6_addr32,
+ sizeof(orig.ipv6_src));
+ memcpy(orig.ipv6_dst, output->ipv6.ct_orig.dst.s6_addr32,
+ sizeof(orig.ipv6_dst));
+ orig.src_port = output->ct.orig_tp.src;
+ orig.dst_port = output->ct.orig_tp.dst;
+ orig.ipv6_proto = output->ct_orig_proto;
+
if (nla_put(skb, OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV6,
sizeof(orig), &orig))
return -EMSGSIZE;
--
2.25.1
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