From dd1cd37f11eef9551a2b70cd96fd28ae0f352051 Mon Sep 17 00:00:00 2001
From: "Kevin P. Fleming" <kpfleming@digium.com>
Date: Mon, 25 Jul 2005 17:13:24 +0000
Subject: [PATCH] ensure SIP_HEADER does not segfault when called on hung-up
 channels (bug #4756, different fix than posted patch)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@6187 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
 channels/chan_sip.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 07c8607fee..d7fe500108 100755
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -8158,6 +8158,13 @@ static char *func_header_read(struct ast_channel *chan, char *cmd, char *data, c
 	}
 
 	p = chan->tech_pvt;
+
+	/* If there is no private structure, this channel is no longer alive */
+	if (!p) {
+		ast_mutex_unlock(&chan->lock);
+		return NULL;
+	}
+
 	content = get_header(&p->initreq, data);
 
 	if (ast_strlen_zero(content)) {
-- 
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