Fix a SIGSEGV during initialization

During the initialisation of 4a-softmixer, when the function
'ProcessOneAvirtSubdev' fails, the function 'AttachOneLoop'
was crashing because it tried to call 'snd_ctl_close' with
a NULL pointer.

This change fixes it. A test is introduced because depending
on the kind of loop, the order of initialization of control
versus subdevs differs.

At the same time, some gotos are improved to avoid a dummy
test -this are also virtual fixes-.

Also a tiny refactor of the 3 times declared variable 'subdev'
is expected to improve the readability.

Bug-AGL: SPEC-2287

Change-Id: Ie5231a1064090d772ea0ea7d86ad8c8d79b38d72
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

1 files changed, 8 insertions, 10 deletions

diff --git a/plugins/alsa/alsa-api-loop.c b/plugins/alsa/alsa-api-loop.c
index 8cf0c4e..e5e6af5 100644
--- a/plugins/alsa/alsa-api-loop.c
+++ b/plugins/alsa/alsa-api-loop.c
@@ -235,6 +235,7 @@ static void freeSubdev(SoftMixerT* mixer, AlsaLoopSubdevT * subdev) {
 
 STATIC AlsaSndLoopT *AttachOneLoop(SoftMixerT *mixer, const char *uid, json_object *argsJ, json_object *streamsJ) {
 
+    AlsaLoopSubdevT * subdev;
     json_object *subdevsJ = NULL, *devicesJ = NULL;
     int error;
 
@@ -302,8 +303,6 @@ STATIC AlsaSndLoopT *AttachOneLoop(SoftMixerT *mixer, const char *uid, json_obje
             }
         }
 
-        AlsaLoopSubdevT * subdev;
-
         switch (json_object_get_type(subdevsJ)) {
             case json_type_object:
                 subdev = ProcessOneSubdev(mixer, loop, subdevsJ);
@@ -334,9 +333,7 @@ STATIC AlsaSndLoopT *AttachOneLoop(SoftMixerT *mixer, const char *uid, json_obje
         AFB_ApiNotice(mixer->api, "nbStreams: %d max.streams: %d", mixer->nbStreams, mixer->max.streams);
 
         if (mixer->nbStreams >= mixer->max.streams)
-            goto fail_snd_card_ctl;
-
-        AlsaLoopSubdevT * subdev;
+            goto fail_snd_card;
 
         // Create AVIRT streams
         switch (json_object_get_type(streamsJ)) {
@@ -363,7 +360,7 @@ STATIC AlsaSndLoopT *AttachOneLoop(SoftMixerT *mixer, const char *uid, json_obje
                 break;
             }
             default:
-                goto fail_snd_card_ctl;
+                goto fail_snd_card;
         }
 
         snd_avirt_card_seal();
@@ -381,17 +378,18 @@ STATIC AlsaSndLoopT *AttachOneLoop(SoftMixerT *mixer, const char *uid, json_obje
 
     return loop;
 
-fail_loop_subdev: {
+fail_loop_subdev:
 	AFB_ApiDebug(mixer->api, "%s cleanup", __func__);
-	AlsaLoopSubdevT * subdev, *tmp;
+	AlsaLoopSubdevT *tmp;
 	cds_list_for_each_entry_safe(subdev, tmp, &loop->subdevs.list, list) {
 		cds_list_del(&subdev->list);
 		freeSubdev(mixer, subdev);
 	}
-}
 
 fail_snd_card_ctl:
-	snd_ctl_close(loop->sndcard->ctl);
+	/* in the case of avirt, loop->sndcard->ctl may be NULL */
+	if (loop->sndcard->ctl)
+		snd_ctl_close(loop->sndcard->ctl);
 fail_snd_card:
 	free(loop->sndcard);
 fail_loop: