From 8c490d636f5dbe289b43cd0c34413aca3e62e2a9 Mon Sep 17 00:00:00 2001
From: Xiao Wang <jasowang@redhat.com>
Date: Mon, 27 Nov 2017 07:07:56 +0100
Subject: [PATCH 5/9] slirp: Fix access to freed memory

RH-Author: Xiao Wang <jasowang@redhat.com>
Message-id: <1511766477-29559-4-git-send-email-jasowang@redhat.com>
Patchwork-id: 77898
O-Subject: [RHEL7.5 qemu-kvm PATCH 3/4] slirp: Fix access to freed memory
Bugzilla: 1508745
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: wexu@redhat.com
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

From: Samuel Thibault <samuel.thibault@ens-lyon.org>

if_start() goes through the slirp->if_fastq and slirp->if_batchq
list of pending messages, and accesses ifm->ifq_so->so_nqueued of its
elements if ifm->ifq_so != NULL.  When freeing a socket, we thus need
to make sure that any pending message for this socket does not refer
to the socket any more.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Tested-by: Brian Candler <b.candler@pobox.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit ea64d5f08817b5e79e17135dce516c7583107f91)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 slirp/socket.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/slirp/socket.c b/slirp/socket.c
index 8e8819c..09b5d3d 100644
--- a/slirp/socket.c
+++ b/slirp/socket.c
@@ -63,6 +63,23 @@ void
 sofree(struct socket *so)
 {
   Slirp *slirp = so->slirp;
+  struct mbuf *ifm;
+
+  for (ifm = (struct mbuf *) slirp->if_fastq.qh_link;
+       (struct quehead *) ifm != &slirp->if_fastq;
+       ifm = ifm->ifq_next) {
+    if (ifm->ifq_so == so) {
+      ifm->ifq_so = NULL;
+    }
+  }
+
+  for (ifm = (struct mbuf *) slirp->if_batchq.qh_link;
+       (struct quehead *) ifm != &slirp->if_batchq;
+       ifm = ifm->ifq_next) {
+    if (ifm->ifq_so == so) {
+      ifm->ifq_so = NULL;
+    }
+  }
 
   if (so->so_emu==EMU_RSH && so->extra) {
 	sofree(so->extra);
-- 
1.8.3.1