[Asterisk-code-review] chan_sip: Fix crash when accessing RURI before initiating outgoing call (asterisk[18])

[George Joseph]

George Joseph has submitted this change. ( https://gerrit.asterisk.org/c/asterisk/+/17665 )

Change subject: chan_sip: Fix crash when accessing RURI before initiating outgoing call
......................................................................

chan_sip: Fix crash when accessing RURI before initiating outgoing call

Attempting to access ${CHANNEL(ruri)} in a pre-dial handler before
initiating an outgoing call will cause Asterisk to crash. This is
because a null field is accessed, resulting in an offset from null and
subsequent memory access violation.

Since RURI is not guaranteed to exist, we now check if the base
pointer is non-null before calculating an offset.

ASTERISK-29772

Change-Id: Icd3b02f07256bbe6615854af5717074087b95a83
---
M channels/sip/dialplan_functions.c
1 file changed, 6 insertions(+), 2 deletions(-)

Approvals:
  George Joseph: Looks good to me, approved; Approved for Submit



diff --git a/channels/sip/dialplan_functions.c b/channels/sip/dialplan_functions.c
index 7c34fc9..74106d1 100644
--- a/channels/sip/dialplan_functions.c
+++ b/channels/sip/dialplan_functions.c
@@ -166,8 +166,12 @@
 	} else if (!strcasecmp(args.param, "uri")) {
 		ast_copy_string(buf, p->uri, buflen);
 	} else if (!strcasecmp(args.param, "ruri")) {
-		char *tmpruri = REQ_OFFSET_TO_STR(&p->initreq, rlpart2);
-		ast_copy_string(buf, tmpruri, buflen);
+		if (p->initreq.data) {
+			char *tmpruri = REQ_OFFSET_TO_STR(&p->initreq, rlpart2);
+			ast_copy_string(buf, tmpruri, buflen);
+		} else {
+			return -1;
+		}
 	} else if (!strcasecmp(args.param, "useragent")) {
 		ast_copy_string(buf, p->useragent, buflen);
 	} else if (!strcasecmp(args.param, "peername")) {

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Gerrit-Project: asterisk
Gerrit-Branch: 18
Gerrit-Change-Id: Icd3b02f07256bbe6615854af5717074087b95a83
Gerrit-Change-Number: 17665
Gerrit-PatchSet: 2
Gerrit-Owner: N A <mail at interlinked.x10host.com>
Gerrit-Reviewer: Friendly Automation
Gerrit-Reviewer: George Joseph <gjoseph at digium.com>
Gerrit-MessageType: merged
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