[asterisk-bugs] [JIRA] (ASTERISK-21190) chan_mgcp crash on chunked m= sdp line

[Matt Jordan (JIRA)]

     [ https://issues.asterisk.org/jira/browse/ASTERISK-21190?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Matt Jordan updated ASTERISK-21190:
-----------------------------------

    Target Release Version/s: 11.7.0
    
> chan_mgcp crash on chunked m= sdp line
> --------------------------------------
>
>                 Key: ASTERISK-21190
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-21190
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Channels/chan_mgcp
>    Affects Versions: 11.2.1
>         Environment: FC 18
>            Reporter: adomjan
>            Assignee: Kinsey Moore
>            Severity: Critical
>      Target Release: 1.8.25.0, 11.7.0
>
>         Attachments: chan_mgcp.c-sscnaf_fix
>
>
> I've got from a bugy MTA a chunked message:
> {noformat}
> 200 61838464 OK
> I: 11B72
> v=0
> o=- 61838464 72562 IN IP4 10.252.5.203
> s=-
> c=IN IP4 10.252.5.203
> b=AS:82
> t=0 0
> m=audio 53
> {noformat}
> asterisk crashed, when parsed the m line
> {noformat}
> #0  0x0000003f85478d50 in strlen () from /lib64/libc.so.6
> No symbol table info available.
> #1  0x00002aaab9a82e12 in process_sdp (sub=0x2aaaac4a3c10, req=0x40cf9010)
>     at chan_mgcp.c:2477
> 	__old = 0x40cfbf61 ""
> 	__len = <value optimized out>
> 	__new = <value optimized out>
> 	m = 0x40cf94b7 "audio 53"
> 	c = <value optimized out>
> 	a = <value optimized out>
> 	host = "10.252.5.203", '\0' <repeats 245 times>
> 	len = 10922
> 	portno = 53
> 	peercapability = <value optimized out>
> 	peerNonCodecCapability = <value optimized out>
> 	sin = {sin_family = 2, sin_port = 13568, sin_addr = {
> {noformat}
> it occured:
> {noformat}
> if (sscanf(m, "audio %30d RTP/AVP %n", &portno, &len) != 1) {
> {noformat}
> the len is unitialized no, the %30d initialized, return value will be 1, but the sscanf() never reach the %n position
> fix:
> {noformat}
> len = 0;
>         if (sscanf(m, "audio %30d RTP/AVP %n", &portno, &len) != 1 || !len) {
>                 ast_log(LOG_WARNING, "Unable to determine port number or codecs for RTP in '%s'\n", m);
>                 return -1;
>         }
> {noformat}
> in another usege not needed:
> {noformat}
>  if (sscanf(codecs, "%30d%n", &codec, &len) != 1) {
> {noformat}
> if return 1 here, the sscanf always will reach the %n positions
> The sip channel driver is effected too many places
> in chan_sip.c:
> {noformat}
> if ((media == SDP_AUDIO && ((sscanf(m, "audio %30u/%30u RTP/AVP %n", &x, &numberofports, &len) == 2 && len > 0)
> {noformat}
> the len value is checked, but missing the len = 0; before sscanf()
> all asterisk versions are affected

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