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authorMichal Kubeček <mkubecek@suse.cz>2016-12-02 11:33:41 +0300
committerDavid S. Miller <davem@davemloft.net>2016-12-02 22:03:20 +0300
commit3de81b758853f0b29c61e246679d20b513c4cfec (patch)
treefe4107dc49e976bfeeacd6cae7b18ac8dd179851 /net/tipc/bearer.c
parentf0d21e894713b43a75bdf2d1b31e587bd5db5341 (diff)
downloadlinux-3de81b758853f0b29c61e246679d20b513c4cfec.tar.xz
tipc: check minimum bearer MTU
Qian Zhang (张谦) reported a potential socket buffer overflow in tipc_msg_build() which is also known as CVE-2016-8632: due to insufficient checks, a buffer overflow can occur if MTU is too short for even tipc headers. As anyone can set device MTU in a user/net namespace, this issue can be abused by a regular user. As agreed in the discussion on Ben Hutchings' original patch, we should check the MTU at the moment a bearer is attached rather than for each processed packet. We also need to repeat the check when bearer MTU is adjusted to new device MTU. UDP case also needs a check to avoid overflow when calculating bearer MTU. Fixes: b97bf3fd8f6a ("[TIPC] Initial merge") Signed-off-by: Michal Kubecek <mkubecek@suse.cz> Reported-by: Qian Zhang (张谦) <zhangqian-c@360.cn> Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc/bearer.c')
-rw-r--r--net/tipc/bearer.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index 975dbeb60ab0..52d74760fb68 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -421,6 +421,10 @@ int tipc_enable_l2_media(struct net *net, struct tipc_bearer *b,
dev = dev_get_by_name(net, driver_name);
if (!dev)
return -ENODEV;
+ if (tipc_mtu_bad(dev, 0)) {
+ dev_put(dev);
+ return -EINVAL;
+ }
/* Associate TIPC bearer with L2 bearer */
rcu_assign_pointer(b->media_ptr, dev);
@@ -610,8 +614,6 @@ static int tipc_l2_device_event(struct notifier_block *nb, unsigned long evt,
if (!b)
return NOTIFY_DONE;
- b->mtu = dev->mtu;
-
switch (evt) {
case NETDEV_CHANGE:
if (netif_carrier_ok(dev))
@@ -624,6 +626,11 @@ static int tipc_l2_device_event(struct notifier_block *nb, unsigned long evt,
tipc_reset_bearer(net, b);
break;
case NETDEV_CHANGEMTU:
+ if (tipc_mtu_bad(dev, 0)) {
+ bearer_disable(net, b);
+ break;
+ }
+ b->mtu = dev->mtu;
tipc_reset_bearer(net, b);
break;
case NETDEV_CHANGEADDR: