red_worker: Check for NULL watches

If we run out of watches slots, we return NULL from watch_add, which
means that the other watch_foo functions may get called with a NULL
parameter, protect them against this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/server/red_worker.c b/server/red_worker.c
index f7c6ccbe..46d46f37 100644
--- a/server/red_worker.c
+++ b/server/red_worker.c
@@ -9514,8 +9514,15 @@ static int common_channel_config_socket(RedChannelClient *rcc)
 
 static void worker_watch_update_mask(SpiceWatch *watch, int event_mask)
 {
-    struct RedWorker *worker = watch->worker;
-    int i = watch - worker->watches;
+    struct RedWorker *worker;
+    int i;
+
+    if (!watch) {
+        return;
+    }
+
+    worker = watch->worker;
+    i = watch - worker->watches;
 
     worker->poll_fds[i].events = 0;
     if (event_mask & SPICE_WATCH_EVENT_READ) {
@@ -9561,6 +9568,10 @@ static SpiceWatch *worker_watch_add(int fd, int event_mask, SpiceWatchFunc func,
 
 static void worker_watch_remove(SpiceWatch *watch)
 {
+    if (!watch) {
+        return;
+    }
+
     /* Note we don't touch the poll_fd here, to avoid the
        poll_fds/watches table entry getting re-used in the same
        red_worker_main loop over the fds as it is removed.