slirp: check sscanf result when emulating ident

When emulating ident in tcp_emu, if the strchr checks passed but the
sscanf check failed, two uninitialized variables would be copied and
sent in the reply, so move this code inside the if(sscanf()) clause.

Signed-off-by: William Bowling <will@wbowling.info>
Cc: qemu-stable@nongnu.org
Cc: secalert@redhat.com
Message-Id: <1551476756-25749-1-git-send-email-will@wbowling.info>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
(cherry picked from commit d3222975c7d6cda9e25809dea05241188457b113)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
index 8d0f94b75fca3830ed0b067b456e9a6dd3973429..473c8b04e668cbd7191267453135675d2fd39939 100644 (file)
--- a/slirp/tcp_subr.c
+++ b/slirp/tcp_subr.c
@@ -662,12 +662,12 @@ tcp_emu(struct socket *so, struct mbuf *m)
                                                        break;
                                                }
                                        }
+                                       so_rcv->sb_cc = snprintf(so_rcv->sb_data,
+                                                                so_rcv->sb_datalen,
+                                                                "%d,%d\r\n", n1, n2);
+                                       so_rcv->sb_rptr = so_rcv->sb_data;
+                                       so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
                                }
-                                so_rcv->sb_cc = snprintf(so_rcv->sb_data,
-                                                         so_rcv->sb_datalen,
-                                                         "%d,%d\r\n", n1, n2);
-                               so_rcv->sb_rptr = so_rcv->sb_data;
-                               so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
                        }
                        m_free(m);
                        return 0;