Patch "tipc: check minimum bearer MTU" has been added to the 4.4-stable tree
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This is a note to let you know that I've just added the patch titled
tipc: check minimum bearer MTU
to the 4.4-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:
tipc-check-minimum-bearer-mtu.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.
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3de81b758853f0b29c61e246679d20b513c4cfecMon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michal=20Kube=C4=8Dek?= <[email protected]>
Date: Fri, 2 Dec 2016 09:33:41 +0100
Subject: tipc: check minimum bearer MTU
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From: Michal Kubeček <[email protected]>
commit 3de81b758853f0b29c61e246679d20b513c4cfec upstream.
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.
[bwh: Backported to 4.4:
- Adjust context
- NETDEV_GOING_DOWN and NETDEV_CHANGEMTU cases in net notifier were combined]
--- net/tipc/bearer.c | 13 +++++++++++-- net/tipc/bearer.h | 13 +++++++++++++ net/tipc/udp_media.c | 5 +++++ 3 files changed, 29 insertions(+), 2 deletions(-)
net/tipc/bearer.c +11 -2
@@ -381,6 +381,10 @@ int tipc_enable_l2_media(struct net *net 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);
@@ -570,14 +574,19 @@ static int tipc_l2_device_event(struct nif (!b_ptr)return NOTIFY_DONE ; - b_ptr->mtu = dev->mtu; -switch (evt) {case NETDEV_CHANGE :if (netif_carrier_ok (dev))break ;case NETDEV_GOING_DOWN : +tipc_reset_bearer (net, b_ptr); +break ;case NETDEV_CHANGEMTU : +if (tipc_mtu_bad (dev,0 )) { +bearer_disable (net, b_ptr); +break ; + } + b_ptr->mtu = dev->mtu;tipc_reset_bearer (net, b_ptr);break ;case NETDEV_CHANGEADDR :
net/tipc/bearer.h +13 -0
@@ -39,6 +39,7 @@#include "netlink.h" #include "core.h" +#include "msg.h" #include <net/genetlink.h> #define MAX_MEDIA 3
@@ -61,6 +62,9 @@#define TIPC_MEDIA_TYPE_IB 2#define TIPC_MEDIA_TYPE_UDP 3 +/* minimum bearer MTU */ +#define TIPC_MIN_BEARER_MTU (MAX_H_SIZE + INT_H_SIZE) +/** * struct tipc_node_map - set of node identifiers * @count: # of nodes in set
@@ -226,4 +230,13 @@ void tipc_bearer_xmit(struct net *net, uvoid tipc_bearer_bc_xmit (struct net *net,u32 bearer_id,struct sk_buff_head *xmitq); +/* check if device MTU is too low for tipc headers */ +static inline bool tipc_mtu_bad (struct net_device *dev,unsigned int reserve) +{ +if (dev->mtu >=TIPC_MIN_BEARER_MTU + reserve) +return false; +netdev_warn (dev,"MTU too low for tipc bearer\n" ); +return true; +} +#endif /* _TIPC_BEARER_H */
net/tipc/udp_media.c +5 -0
@@ -376,6 +376,11 @@ static int tipc_udp_enable(struct net *n udp_conf.local_ip.s_addr =htonl (INADDR_ANY ); udp_conf.use_udp_checksums = false; ub->ifindex = dev->ifindex; +if (tipc_mtu_bad (dev,sizeof (struct iphdr ) + +sizeof (struct udphdr ))) { + err = -EINVAL ; + goto err; + } b->mtu = dev->mtu -sizeof (struct iphdr ) -sizeof (struct udphdr );#if IS_ENABLED (CONFIG_IPV6 )
Patches currently in stable-queue which might be from [email protected] are
queue-4.4/tipc-check-minimum-bearer-mtu.patch