[Spice-commits] server/red_channel.c

Hans de Goede jwrdegoede at kemper.freedesktop.org
Fri Jul 5 06:00:10 PDT 2013

 server/red_channel.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

New commits:
commit 53488f0275d6c8a121af49f7ac817d09ce68090d
Author: David Gibson <david at gibson.dropbear.id.au>
Date:   Fri Jul 5 17:11:46 2013 +1000

    Use RING_FOREACH_SAFE in red_channel.c functions which are missing it
    Currently, both red_channel_pipes_add_type() and
    red_channel_pipes_add_empty_msg() use plaing RING_FOREACH() which is not
    safe versus removals from the ring within the loop body.
    Although it's rare, such a removal can occur in both cases.  In the case
    of red_channel_pipes_add_type() we have:
        -> red_channel_client_pipe_add_type()
            -> red_channel_client_push()
    And in the case of red_channel_client_pipes_add_empty_msg() we have:
        -> red_channel_client_pipe_add_empty_msg()
            -> red_channel_client_push()
    But red_channel_client_push() can cause a removal from the clients ring if
    a network error occurs:
        -> red_channel_client_send()
            -> red_peer_handle_outgoing()
                -> handler->cb->on_error callback
                =  red_channel_client_default_peer_on_error()
                    -> red_channel_client_disconnect()
                        -> red_channel_remove_client()
                            -> ring_remove()
    When this error path does occur, the assertion in RING_FOREACH()'s
    ring_next() trips, and the process containing the spice server is aborted.
    i.e. your whole VM dies, as a result of an unfortunately timed network
    error on the spice channel.
    Please apply.
    Signed-off-by: David Gibson <dgibson at redhat.com>

diff --git a/server/red_channel.c b/server/red_channel.c
index c0b1781..8742008 100644
--- a/server/red_channel.c
+++ b/server/red_channel.c
@@ -1572,9 +1572,9 @@ void red_channel_client_pipe_add_type(RedChannelClient *rcc, int pipe_item_type)
 void red_channel_pipes_add_type(RedChannel *channel, int pipe_item_type)
-    RingItem *link;
+    RingItem *link, *next;
-    RING_FOREACH(link, &channel->clients) {
+    RING_FOREACH_SAFE(link, next, &channel->clients) {
             SPICE_CONTAINEROF(link, RedChannelClient, channel_link),
@@ -1593,9 +1593,9 @@ void red_channel_client_pipe_add_empty_msg(RedChannelClient *rcc, int msg_type)
 void red_channel_pipes_add_empty_msg(RedChannel *channel, int msg_type)
-    RingItem *link;
+    RingItem *link, *next;
-    RING_FOREACH(link, &channel->clients) {
+    RING_FOREACH_SAFE(link, next, &channel->clients) {
             SPICE_CONTAINEROF(link, RedChannelClient, channel_link),

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