rpc: Fix crash on error paths of message dispatching

This patch resolves CVE-2013-0170:
https://bugzilla.redhat.com/show_bug.cgi?id=893450

When reading and dispatching of a message failed the message was freed
but wasn't removed from the message queue.

After that when the connection was about to be closed the pointer for
the message was still present in the queue and it was passed to
virNetMessageFree which tried to call the callback function from an
uninitialized pointer.

This patch removes the message from the queue before it's freed.

* rpc/virnetserverclient.c: virNetServerClientDispatchRead:
    - avoid use after free of RPC messages

(cherry picked from commit 46532e3e8ed5f5a736a02f67d6c805492f9ca720)

diff --git a/src/rpc/virnetserverclient.c b/src/rpc/virnetserverclient.c
index 67600fd00af2f323f7a1054ab944deb90b0a1293..383813637efb98a2e9cd253af39bca4b4ea34cc5 100644 (file)
--- a/src/rpc/virnetserverclient.c
+++ b/src/rpc/virnetserverclient.c
@@ -840,6 +840,7 @@ readmore:
 
         /* Decode the header so we can use it for routing decisions */
         if (virNetMessageDecodeHeader(msg) < 0) {
+            virNetMessageQueueServe(&client->rx);
             virNetMessageFree(msg);
             client->wantClose = true;
             return;
@@ -849,6 +850,7 @@ readmore:
          * file descriptors */
         if (msg->header.type == VIR_NET_CALL_WITH_FDS &&
             virNetMessageDecodeNumFDs(msg) < 0) {
+            virNetMessageQueueServe(&client->rx);
             virNetMessageFree(msg);
             client->wantClose = true;
             return; /* Error */
@@ -858,6 +860,7 @@ readmore:
         for (i = msg->donefds ; i < msg->nfds ; i++) {
             int rv;
             if ((rv = virNetSocketRecvFD(client->sock, &(msg->fds[i]))) < 0) {
+                virNetMessageQueueServe(&client->rx);
                 virNetMessageFree(msg);
                 client->wantClose = true;
                 return;