chan_sip.c: Fix crash processing CANCEL.

Check if initreq data string exists before using it when processing a
CANCEL request.

ASTERISK-27666

Change-Id: Id1d0f0fa4ec94e81b332b2973d93e5a14bb4cc97

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 7a94517c4d73fb34d1a759c81d9f9ee7e04852f4..563cea886bc4fcf7723fb7543d43fbfd2e359329 100644 (file)
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -27207,7 +27207,7 @@ static int handle_request_cancel(struct sip_pvt *p, struct sip_request *req)
        } else {
                sip_scheddestroy(p, DEFAULT_TRANS_TIMEOUT);
        }
-       if (ast_str_strlen(p->initreq.data) > 0) {
+       if (p->initreq.data && ast_str_strlen(p->initreq.data) > 0) {
                struct sip_pkt *pkt, *prev_pkt;
                /* If the CANCEL we are receiving is a retransmission, and we already have scheduled
                 * a reliable 487, then we don't want to schedule another one on top of the previous