chan_mgcp: Properly handle malformed media lines

This corrects a situation in which a media line was not parsed properly
and resulted in a crash.

(closes issue ASTERISK-21190)
Reported by: adomjan
Patches:
    chan_mgcp.c-sscnaf_fix uploaded by adomjan (License 5448)
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Merged revisions 401537 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 401538 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 401539 from http://svn.asterisk.org/svn/asterisk/branches/12

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@401540 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/channels/chan_mgcp.c b/channels/chan_mgcp.c
index a659a2a..84fb3b2 100644 (file)
--- a/channels/chan_mgcp.c
+++ b/channels/chan_mgcp.c
@@ -1971,7 +1971,7 @@ static int process_sdp(struct mgcp_subchannel *sub, struct mgcp_request *req)
        char *c;
        char *a;
        char host[258];
-       int len;
+       int len = 0;
        int portno;
        struct ast_format_cap *peercap;
        int peerNonCodecCapability;
@@ -2001,8 +2001,8 @@ static int process_sdp(struct mgcp_subchannel *sub, struct mgcp_request *req)
                ast_log(LOG_WARNING, "Unable to lookup host in c= line, '%s'\n", c);
                return -1;
        }
-       if (sscanf(m, "audio %30d RTP/AVP %n", &portno, &len) != 1) {
-               ast_log(LOG_WARNING, "Unable to determine port number for RTP in '%s'\n", m);
+       if (sscanf(m, "audio %30d RTP/AVP %n", &portno, &len) != 1 || !len) {
+               ast_log(LOG_WARNING, "Malformed media stream descriptor: %s\n", m);
                return -1;
        }
        sin.sin_family = AF_INET;