pjsip_messaging, pjsip_header_funcs: Crashes due to NULL pointer dereferences

Both res_pjsip_messaging and res_pjsip_header_funcs were causing asterisk to
crash because they were trying to dereference a NULL pointer.

In the case of res_pjsip_messaging it was attempting to "print" a contact
header that did not exist.  In fact contact headers should not be part of
a SIP MESSAGE, so the offending code was simply removed.

In the case of res_pjsip_header_funcs a null private channel tech was being
passed to the function and then later dereferenced.  Added null checks (and
error logging) to the read/write function handlers to guard against crashing.

(closes issue ASTERISK-22821)
Reported by: Anthony Messina
........

Merged revisions 402757 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@402758 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 10 insertions, 0 deletions

diff --git a/res/res_pjsip_header_funcs.c b/res/res_pjsip_header_funcs.c
index 7425d8f59..11ab44c10 100644
--- a/res/res_pjsip_header_funcs.c
+++ b/res/res_pjsip_header_funcs.c
@@ -452,6 +452,11 @@ static int func_read_header(struct ast_channel *chan, const char *function, char
 						 AST_APP_ARG(header_name); AST_APP_ARG(header_number););
 	AST_STANDARD_APP_ARGS(args, data);
 
+	if (!channel) {
+		ast_log(LOG_ERROR, "This function requires a PJSIP channel.\n");
+		return -1;
+	}
+
 	if (ast_strlen_zero(args.action)) {
 		ast_log(AST_LOG_ERROR, "This function requires an action.\n");
 		return -1;
@@ -506,6 +511,11 @@ static int func_write_header(struct ast_channel *chan, const char *cmd, char *da
 						 AST_APP_ARG(header_name); AST_APP_ARG(header_number););
 	AST_STANDARD_APP_ARGS(args, data);
 
+	if (!channel) {
+		ast_log(LOG_ERROR, "This function requires a PJSIP channel.\n");
+		return -1;
+	}
+
 	if (ast_strlen_zero(args.action)) {
 		ast_log(AST_LOG_ERROR, "This function requires an action.\n");
 		return -1;