slirp: Fix access to freed memory

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 <[email protected]> Tested-by: Brian Candler <[email protected]> Reviewed-by: Stefan Hajnoczi <[email protected]>
dreddy · Nov 14, 2016 · ea64d5f · ea64d5f
1 parent 83c83f9
commit ea64d5f
Showing 1 changed file with 17 additions and 0 deletions.
diff --git a/slirp/socket.c b/slirp/socket.c
@@ -66,6 +66,23 @@ 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);