core_local: local channel data not being properly unref'ed and unlocked

In an earlier version of Asterisk a local channel [un]lock all functions were
added in order to keep a crash from occurring when a channel hung up too early
during an attended transfer. Unfortunately, when a transfer failure occurs and
depending on the timing, the local channels sometime do not get properly
unlocked and deref'ed after being locked and ref'ed. This happens because the
underlying local channel structure gets NULLed out before unlocking.

This patch reworks those [un]lock functions and makes sure the values that get
locked and ref'ed later get unlocked and deref'ed.

ASTERISK-27074 #close

Change-Id: Ice96653e29bd9d6674ed5f95feb6b448ab148b09

1 files changed, 19 insertions, 23 deletions

diff --git a/main/core_local.c b/main/core_local.c
index aa232a4b6..23c7cce9d 100644
--- a/main/core_local.c
+++ b/main/core_local.c
@@ -233,43 +233,39 @@ struct local_pvt {
 	char exten[AST_MAX_EXTENSION];
 };
 
-void ast_local_lock_all(struct ast_channel *chan, struct ast_channel **outchan,
-			struct ast_channel **outowner)
+void ast_local_lock_all(struct ast_channel *chan, void **tech_pvt,
+	struct ast_channel **base_chan, struct ast_channel **base_owner)
 {
 	struct local_pvt *p = ast_channel_tech_pvt(chan);
 
-	*outchan = NULL;
-	*outowner = NULL;
+	*tech_pvt = NULL;
+	*base_chan = NULL;
+	*base_owner = NULL;
 
 	if (p) {
-		ao2_ref(p, 1);
-		ast_unreal_lock_all(&p->base, outchan, outowner);
+		*tech_pvt = ao2_bump(p);
+		ast_unreal_lock_all(&p->base, base_chan, base_owner);
 	}
 }
 
-void ast_local_unlock_all(struct ast_channel *chan)
+void ast_local_unlock_all(void *tech_pvt, struct ast_channel *base_chan,
+	struct ast_channel *base_owner)
 {
-	struct local_pvt *p = ast_channel_tech_pvt(chan);
-	struct ast_unreal_pvt *base;
-
-	if (!p) {
-		return;
+	if (base_chan) {
+		ast_channel_unlock(base_chan);
+		ast_channel_unref(base_chan);
 	}
 
-	base = &p->base;
-
-	if (base->owner) {
-		ast_channel_unlock(base->owner);
-		ast_channel_unref(base->owner);
+	if (base_owner) {
+		ast_channel_unlock(base_owner);
+		ast_channel_unref(base_owner);
 	}
 
-	if (base->chan) {
-		ast_channel_unlock(base->chan);
-		ast_channel_unref(base->chan);
+	if (tech_pvt) {
+		struct local_pvt *p = tech_pvt;
+		ao2_unlock(&p->base);
+		ao2_ref(tech_pvt, -1);
 	}
-
-	ao2_unlock(base);
-	ao2_ref(p, -1);
 }
 
 struct ast_channel *ast_local_get_peer(struct ast_channel *ast)