audiod: Check pointers passed to btr_get_node_start().

If the receiver or writer buffer tree node pointer is NULL, we'll segfault due
to a a NULL pointer dereference in btr_get_node_start(). Although this might
not be triggerable, it does not hurt to be defensive here.

diff --git a/audiod.c b/audiod.c
index aefac612b480af2d6f1c857b5225f3d042b68ff4..40603c4eff782b0f945ccab6f5193e99f78b7462 100644 (file)
--- a/audiod.c
+++ b/audiod.c
@@ -250,7 +250,7 @@ char *get_time_string(int slot_num)
         */
        length = stat_task->length_seconds;
        tmp = &stat_task->server_stream_start;
-       if (s && s->wns) { /* writer active in this slot */
+       if (s && s->wns && s->wns[0].btrn) { /* writer active in this slot */
                btr_get_node_start(s->wns[0].btrn, &wstime);
                if (wstime.tv_sec != 0) { /* writer wrote something */
                        if (s->server_stream_start.tv_sec == 0) {
@@ -267,7 +267,7 @@ char *get_time_string(int slot_num)
                tv_diff(tmp, &stat_task->sa_time_diff, &sss);
        else
                tv_add(tmp, &stat_task->sa_time_diff, &sss);
-       if (!s || !s->wns) {
+       if (!s || !s->wns || !s->wns[0].btrn) {
                struct timeval diff;
                tv_diff(now, &sss, &diff);
                seconds = diff.tv_sec + stat_task->offset_seconds;
@@ -276,11 +276,14 @@ char *get_time_string(int slot_num)
        tv_diff(now, &wstime, &wtime);
        //PARA_CRIT_LOG("offset %d\n", s->offset_seconds);
        seconds = s->offset_seconds;
-       btr_get_node_start(s->receiver_node->btrn, &rstime);
-       ret = tv_diff(&rstime, &sss, &rskip);
-       if (ret > 0) { /* audiod was started in the middle of the stream */
-               tv_add(&wtime, &rskip, &sum);
-               seconds += sum.tv_sec;
+       if (s->receiver_node->btrn) {
+               btr_get_node_start(s->receiver_node->btrn, &rstime);
+               ret = tv_diff(&rstime, &sss, &rskip);
+               if (ret > 0) { /* audiod was started in the middle of the stream */
+                       tv_add(&wtime, &rskip, &sum);
+                       seconds += sum.tv_sec;
+               } else
+                       seconds += wtime.tv_sec;
        } else
                seconds += wtime.tv_sec;
 out: