slirp: udp: fix NULL pointer dereference because of uninitialized socketv2.3.1v2.3.0-rc4v2.3.0-rc3v2.3.0-rc2v2.3.0-rc1v2.3.0-rc0v2.3.0v2.2.1v2.2.0-rc5v2.2.0-rc4v2.2.0-rc3v2.2.0-rc2v2.2.0-rc1v2.2.0-rc0v2.2.0

When guest sends udp packet with source port and source addr 0,
uninitialized socket is picked up when looking for matching and already
created udp sockets, and later passed to sosendto() where NULL pointer
dereference is hit during so->slirp->vnetwork_mask.s_addr access.

Fix this by checking that the socket is not just a socket stub.

This is CVE-2014-3640.

Signed-off-by: Petr Matousek <pmatouse@redhat.com>
Reported-by: Xavier Mehrenberger <xavier.mehrenberger@airbus.com>
Reported-by: Stephane Duverger <stephane.duverger@eads.net>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Message-id: 20140918063537.GX9321@dhcp-25-225.brq.redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/udp.c b/udp.c
index 9bc264f..5121099 100644
--- a/udp.c
+++ b/udp.c
@@ -150,7 +150,7 @@ void udp_input(register struct mbuf *m, int iphlen)
      * Locate pcb for datagram.
      */
     so = slirp->udp_last_so;
-    if (so->so_lport != uh->uh_sport ||
+    if (so == &slirp->udb || so->so_lport != uh->uh_sport ||
         so->so_laddr.s_addr != ip->ip_src.s_addr) {
         struct socket *tmp;