A use-after-free vulnerability in rpcbind causing remotely triggerable crash was found. Rpcbind crashes in svc_dodestroy when trying to free a corrupted xprt->xp_netid pointer, which contains a sockaddr_in. Here's how it happens (as explained in http://www.spinics.net/lists/linux-nfs/msg53045.html ) :

 - A PMAP_CALLIT call comes in on IPv4 UDP

 - rpcbind duplicates the caller's address to a netbuf and stores
	it in FINFO[0].caller_addr. caller_addr->buf now points to a
    memory region A with a size of 16 bytes

 - rpcbind forwards the call to the local service, receives a reply

 - when processing the reply, it does this in xprt_set_caller:
     xprt->xp_rtaddr = *FINFO[0].caller_addr
   where xprt is the UDP transport on which it received the
   PMAP_CALLIT request.

   It sends out the reply, and then frees the netbuf caller_addr and
   caller_addr.buf.
   However, it does not clear xp_rtaddr, so xp_rtaddr.buf now refers
   to memory region A, which is free.

 - When the next call comes in on the UDP/IPv4 socket, svc_dg_recv
   will be called, which will set xp_rtaddr to the client's address.
   It will reuse the buffer inside xp_rtaddr, ie it will write a
   sockaddr_in to region A.

So, this explains how memory gets corrupted. Here's why that 
eventually lead to a crash in svc_dodestroy.

Some time down the road, an incoming TCP connection is accepted,
allocating a fresh SVCXPRT. The memory region A is inside the
new SVCXPRT

 - While processing the TCP call, another UDP call comes in, again
   overwriting region A with the client's address

 - TCP client closes connection. In svc_destroy, we now trip over
   the garbage left in region A

CVE assignment:

http://seclists.org/oss-sec/2015/q3/566