tipc: Prevent invalid memory access when sending to configuration service

Reject TIPC configuration service messages without a full message
header.  Previously, an application that sent a message to the
configuration service that was too short could cause the validation
code to access an uninitialized field in the msghdr structure,
resulting in a memory access exception.

Signed-off-by: Allan Stephens <Allan.Stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 893ca6eb5b41..125dcb0737b2 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -493,6 +493,8 @@ static int dest_name_check(struct sockaddr_tipc *dest, struct msghdr *m)
         if (likely(dest->addr.name.name.type != TIPC_CFG_SRV))
                 return -EACCES;
 
+        if (!m->msg_iovlen || (m->msg_iov[0].iov_len < sizeof(hdr)))
+                return -EMSGSIZE;
         if (copy_from_user(&hdr, m->msg_iov[0].iov_base, sizeof(hdr)))
                 return -EFAULT;
         if ((ntohs(hdr.tcm_type) & 0xC000) && (!capable(CAP_NET_ADMIN)))