ensure SIP_HEADER does not segfault when called on hung-up channels (bug #4756, diffe...

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@6187 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 07c8607fee2f464b620a744cfb84a8e40f5da793..d7fe5001088420140e7c071af552b3f8d6157e11 100755 (executable)
--- 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)) {