From d01f7b6dd84dcadabbc305d77e529c102d93f676 Mon Sep 17 00:00:00 2001
From: Richard Mudgett <rmudgett@digium.com>
Date: Fri, 1 Apr 2011 23:15:42 +0000
Subject: [PATCH] When a call going out an NT-PTMP port gets rejected, Asterisk
 crashes.

If a call is sent to an ISDN phone that rejects the call with
RELEASE_COMPLETE(cause: call reject(21), or busy(17)) Asterisk crashes.

I could not get my setup to crash.  However, I could see the possibility
from a race condition between queuing an AST_CONTROL_BUSY to the core and
then queueing an AST_CONTROL_HANGUP.  If the AST_CONTROL_BUSY is processed
before the AST_CONTROL_HANGUP is queued, the ast_channel could be
destroyed out from under chan_misdn.

Avoid this particular crash scenario by not queueing the
AST_CONTROL_HANGUP if the AST_CONTROL_BUSY was queued.

(closes issue #18408)
Reported by: wimpy
Patches:
      issue18408_v1.8.patch uploaded by rmudgett (license 664)
Tested by: rmudgett, wimpy

JIRA SWP-2679


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@312509 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
 channels/chan_misdn.c | 37 ++++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/channels/chan_misdn.c b/channels/chan_misdn.c
index eb6e9bd5da..76e6eb8d9c 100644
--- a/channels/chan_misdn.c
+++ b/channels/chan_misdn.c
@@ -679,7 +679,7 @@ static ast_mutex_t cl_te_lock;
 static enum event_response_e
 cb_events(enum event_e event, struct misdn_bchannel *bc, void *user_data);
 
-static void send_cause2ast(struct ast_channel *ast, struct misdn_bchannel*bc, struct chan_list *ch);
+static int send_cause2ast(struct ast_channel *ast, struct misdn_bchannel *bc, struct chan_list *ch);
 
 static void cl_queue_chan(struct chan_list *chan);
 
@@ -8365,8 +8365,7 @@ static void hangup_chan(struct chan_list *ch, struct misdn_bchannel *bc)
 		cb_log(2, port, " --> hangup\n");
 		ch->need_hangup = 0;
 		ch->need_queue_hangup = 0;
-		if (ch->ast) {
-			send_cause2ast(ch->ast, bc, ch);
+		if (ch->ast && send_cause2ast(ch->ast, bc, ch)) {
 			ast_hangup(ch->ast);
 		}
 		return;
@@ -8374,13 +8373,15 @@ static void hangup_chan(struct chan_list *ch, struct misdn_bchannel *bc)
 
 	if (!ch->need_queue_hangup) {
 		cb_log(2, port, " --> No need to queue hangup\n");
+		return;
 	}
 
 	ch->need_queue_hangup = 0;
 	if (ch->ast) {
-		send_cause2ast(ch->ast, bc, ch);
-		ast_queue_hangup_with_cause(ch->ast, bc->cause);
-		cb_log(2, port, " --> queue_hangup\n");
+		if (send_cause2ast(ch->ast, bc, ch)) {
+			ast_queue_hangup_with_cause(ch->ast, bc->cause);
+			cb_log(2, port, " --> queue_hangup\n");
+		}
 	} else {
 		cb_log(1, port, "Cannot hangup chan, no ast\n");
 	}
@@ -8654,26 +8655,31 @@ static void do_immediate_setup(struct misdn_bchannel *bc, struct chan_list *ch,
 	}
 }
 
+/*!
+ * \retval -1 if can hangup after calling.
+ * \retval 0 if cannot hangup after calling.
+ */
+static int send_cause2ast(struct ast_channel *ast, struct misdn_bchannel *bc, struct chan_list *ch)
+{
+	int can_hangup;
 
-
-static void send_cause2ast(struct ast_channel *ast, struct misdn_bchannel *bc, struct chan_list *ch) {
 	if (!ast) {
 		chan_misdn_log(1, 0, "send_cause2ast: No Ast\n");
-		return;
+		return 0;
 	}
 	if (!bc) {
 		chan_misdn_log(1, 0, "send_cause2ast: No BC\n");
-		return;
+		return 0;
 	}
 	if (!ch) {
 		chan_misdn_log(1, 0, "send_cause2ast: No Ch\n");
-		return;
+		return 0;
 	}
 
 	ast->hangupcause = bc->cause;
 
+	can_hangup = -1;
 	switch (bc->cause) {
-
 	case AST_CAUSE_UNALLOCATED:
 	case AST_CAUSE_NO_ROUTE_TRANSIT_NET:
 	case AST_CAUSE_NO_ROUTE_DESTINATION:
@@ -8700,15 +8706,16 @@ static void send_cause2ast(struct ast_channel *ast, struct misdn_bchannel *bc, s
 			chan_misdn_log(1, bc ? bc->port : 0, "Queued busy already\n");
 			break;
 		}
+		ch->need_busy = 0;
 
 		chan_misdn_log(1, bc ? bc->port : 0, " --> * SEND: Queue Busy pid:%d\n", bc ? bc->pid : -1);
-
 		ast_queue_control(ast, AST_CONTROL_BUSY);
 
-		ch->need_busy = 0;
-
+		/* The BUSY is likely to cause a hangup or the user needs to hear it. */
+		can_hangup = 0;
 		break;
 	}
+	return can_hangup;
 }
 
 
-- 
2.47.2