When traversing the list of channel variables here in transmit_invite(), the

asterisk channel must be locked, as this data may change at any time.

(I have seen numerous reports of crashes related to the handling of channel
variables.  There are a couple of issues on the bug tracker related to it,
but it has also been noted on IRC and mailing lists.  So, I am finding and
fixing some places where channel variables are handled improperly.)

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@88768 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 958680ba765308e95873e9c9cc909d949fe4d4f0..23fe8f907d4e590c73739153913ea1d17744a2b4 100644 (file)
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -6954,8 +6954,12 @@ static int transmit_invite(struct sip_pvt *p, int sipmethod, int sdp, int init)
        add_header(&req, "Allow", ALLOWED_METHODS);
        add_header(&req, "Supported", SUPPORTED_EXTENSIONS);
        if (p->options && p->options->addsipheaders && p->owner) {
-               struct ast_channel *ast = p->owner; /* The owner channel */
-               struct varshead *headp = &ast->varshead;
+               struct ast_channel *chan = p->owner; /* The owner channel */
+               struct varshead *headp;
+       
+               ast_channel_lock(chan);
+
+               headp = &chan->varshead;
 
                if (!headp)
                        ast_log(LOG_WARNING,"No Headp for the channel...ooops!\n");
@@ -6986,6 +6990,8 @@ static int transmit_invite(struct sip_pvt *p, int sipmethod, int sdp, int init)
                                }
                        }
                }
+
+               ast_channel_unlock(chan);
        }
        if (sdp) {
                if (p->udptl && p->t38.state == T38_LOCAL_DIRECT) {