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authorMichal Kubeček <mkubecek@suse.cz>2016-12-02 09:33:41 +0100
committerDavid S. Miller <davem@davemloft.net>2016-12-02 14:03:20 -0500
commit3de81b758853f0b29c61e246679d20b513c4cfec (patch)
treefe4107dc49e976bfeeacd6cae7b18ac8dd179851 /net/tipc/bearer.h
parentf0d21e894713b43a75bdf2d1b31e587bd5db5341 (diff)
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.h')
-rw-r--r--net/tipc/bearer.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/net/tipc/bearer.h b/net/tipc/bearer.h
index 78892e2f53e3..278ff7f616f9 100644
--- a/net/tipc/bearer.h
+++ b/net/tipc/bearer.h
@@ -39,6 +39,7 @@
#include "netlink.h"
#include "core.h"
+#include "msg.h"
#include <net/genetlink.h>
#define MAX_MEDIA 3
@@ -59,6 +60,9 @@
#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_media_addr - destination address used by TIPC bearers
* @value: address info (format defined by media)
@@ -215,4 +219,13 @@ void tipc_bearer_xmit(struct net *net, u32 bearer_id,
void 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 */