h225: Fix use after free.

next_tvb_add_handle() allocates memory in packet scope.
When dissecting another packet from dissect_h225_h225_RasMessage() handler [it don't call next_tvb_init()]
next_tvb_add_handle() will write to freed pointer.

Fix by calling next_tvb_init() after leaving scope in order to clear list->last pointer.

ASAN report:
ERROR: AddressSanitizer: heap-use-after-free on address 0x6070000854f0 at pc 0x00000208574a bp 0x7ffca839cf00 sp 0x7ffca839cef8
WRITE of size 8 at 0x6070000854f0 thread T0
    #0 0x2085749 in next_tvb_add_handle /src/wireshark/epan/next_tvb.c
    #1 0xef8728 in dissect_h225_ParallelH245Control_item /src/wireshark/epan/dissectors/./asn1/h225/h225.cnf:368:3
(...)
    #21 0x168f460 in dissect_per_sequence /src/wireshark/epan/dissectors/packet-per.c:1920:12
    #22 0xef31d3 in dissect_h225_InfoRequestResponse /src/wireshark/epan/dissectors/./asn1/h225/h225.cnf:910:12
    #23 0x168e7db in dissect_per_choice /src/wireshark/epan/dissectors/packet-per.c
    #24 0xeed6e3 in dissect_h225_RasMessage /src/wireshark/epan/dissectors/./asn1/h225/h225.cnf:298:12
    #25 0xef97af in dissect_RasMessage_PDU /src/wireshark/epan/dissectors/./asn1/h225/h225.cnf:339:12
    #26 0xeef872 in dissect_h225_h225_RasMessage /src/wireshark/epan/dissectors/./asn1/h225/packet-h225-template.c:385:12

0x6070000854f0 is located 0 bytes inside of 72-byte region [0x6070000854f0,0x607000085538)
freed by thread T0 here:
    #0 0x4e2528 in __interceptor_cfree.localalias.0 /src/llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:76
    #1 0x21263a1 in wmem_simple_free_all /src/wireshark/epan/wmem/wmem_allocator_simple.c:107:9
    #2 0x205aa4d in wmem_leave_packet_scope /src/wireshark/epan/wmem/wmem_scopes.c:81:5
(...)

previously allocated by thread T0 here:
    #0 0x4e26e8 in __interceptor_malloc /src/llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:88
    #1 0x225c588 in g_malloc (/out/fuzzshark_test+0x225c588)
    #2 0x20855e0 in next_tvb_add_handle /src/wireshark/epan/next_tvb.c:40:10
    #3 0xef8728 in dissect_h225_ParallelH245Control_item /src/wireshark/epan/dissectors/./asn1/h225/h225.cnf:368:3

Found by oss-fuzz/5921

Change-Id: Iea006914a9e0c433d2073f6f4c7a2973d5a33a11
Link: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5921
Reviewed-on: https://code.wireshark.org/review/25593
Petri-Dish: Jakub Zawadzki <darkjames-ws@darkjames.pl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

2 files changed, 29 insertions, 5 deletions

diff --git a/epan/dissectors/asn1/h225/packet-h225-template.c b/epan/dissectors/asn1/h225/packet-h225-template.c
index e39971dfc4..c92f536238 100644
--- a/epan/dissectors/asn1/h225/packet-h225-template.c
+++ b/epan/dissectors/asn1/h225/packet-h225-template.c
@@ -44,6 +44,7 @@
 #include <epan/tap.h>
 #include <epan/stat_tap_ui.h>
 #include <epan/rtd_table.h>
+#include "packet-frame.h"
 #include "packet-tpkt.h"
 #include "packet-per.h"
 #include "packet-h225.h"
@@ -329,6 +330,14 @@ h225ras_call_t * append_h225ras_call(h225ras_call_t *prev_call, packet_info *pin
   return h225ras_call;
 }
 
+static void
+h225_frame_end(void)
+{
+  /* next_tvb pointers are allocated in packet scope, clear it. */
+  next_tvb_init(&h245_list);
+  next_tvb_init(&tp_list);
+}
+
 static int
 dissect_h225_H323UserInformation(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
 {
@@ -342,6 +351,7 @@ dissect_h225_H323UserInformation(tvbuff_t *tvb, packet_info *pinfo, proto_tree *
   h225_pi->msg_type = H225_CS;
   p_add_proto_data(pinfo->pool, pinfo, proto_h225, 0, h225_pi);
 
+  register_frame_end_routine(pinfo, h225_frame_end);
   next_tvb_init(&h245_list);
   next_tvb_init(&tp_list);
 
@@ -377,6 +387,8 @@ dissect_h225_h225_RasMessage(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree
   h225_pi->msg_type = H225_RAS;
   p_add_proto_data(pinfo->pool, pinfo, proto_h225, 0, h225_pi);
 
+  register_frame_end_routine(pinfo, h225_frame_end);
+
   col_set_str(pinfo->cinfo, COL_PROTOCOL, PSNAME);
 
   it=proto_tree_add_protocol_format(tree, proto_h225, tvb, offset, -1, PSNAME" RAS");
diff --git a/epan/dissectors/packet-h225.c b/epan/dissectors/packet-h225.c
index 65fe553597..ad85e2e13f 100644
--- a/epan/dissectors/packet-h225.c
+++ b/epan/dissectors/packet-h225.c
@@ -52,6 +52,7 @@
 #include <epan/tap.h>
 #include <epan/stat_tap_ui.h>
 #include <epan/rtd_table.h>
+#include "packet-frame.h"
 #include "packet-tpkt.h"
 #include "packet-per.h"
 #include "packet-h225.h"
@@ -908,7 +909,7 @@ static int hf_h225_stopped = -1;                  /* NULL */
 static int hf_h225_notAvailable = -1;             /* NULL */
 
 /*--- End of included file: packet-h225-hf.c ---*/
-#line 128 "./asn1/h225/packet-h225-template.c"
+#line 129 "./asn1/h225/packet-h225-template.c"
 
 /* Initialize the subtree pointers */
 static gint ett_h225 = -1;
@@ -1156,7 +1157,7 @@ static gint ett_h225_ServiceControlResponse = -1;
 static gint ett_h225_T_result = -1;
 
 /*--- End of included file: packet-h225-ett.c ---*/
-#line 132 "./asn1/h225/packet-h225-template.c"
+#line 133 "./asn1/h225/packet-h225-template.c"
 
 /* Preferences */
 static guint h225_tls_port = TLS_PORT_CS;
@@ -7823,7 +7824,7 @@ static int dissect_RasMessage_PDU(tvbuff_t *tvb _U_, packet_info *pinfo _U_, pro
 
 
 /*--- End of included file: packet-h225-fn.c ---*/
-#line 248 "./asn1/h225/packet-h225-template.c"
+#line 249 "./asn1/h225/packet-h225-template.c"
 
 /* Forward declaration we need below */
 void proto_reg_handoff_h225(void);
@@ -7908,6 +7909,14 @@ h225ras_call_t * append_h225ras_call(h225ras_call_t *prev_call, packet_info *pin
   return h225ras_call;
 }
 
+static void
+h225_frame_end(void)
+{
+  /* next_tvb pointers are allocated in packet scope, clear it. */
+  next_tvb_init(&h245_list);
+  next_tvb_init(&tp_list);
+}
+
 static int
 dissect_h225_H323UserInformation(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
 {
@@ -7921,6 +7930,7 @@ dissect_h225_H323UserInformation(tvbuff_t *tvb, packet_info *pinfo, proto_tree *
   h225_pi->msg_type = H225_CS;
   p_add_proto_data(pinfo->pool, pinfo, proto_h225, 0, h225_pi);
 
+  register_frame_end_routine(pinfo, h225_frame_end);
   next_tvb_init(&h245_list);
   next_tvb_init(&tp_list);
 
@@ -7956,6 +7966,8 @@ dissect_h225_h225_RasMessage(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree
   h225_pi->msg_type = H225_RAS;
   p_add_proto_data(pinfo->pool, pinfo, proto_h225, 0, h225_pi);
 
+  register_frame_end_routine(pinfo, h225_frame_end);
+
   col_set_str(pinfo->cinfo, COL_PROTOCOL, PSNAME);
 
   it=proto_tree_add_protocol_format(tree, proto_h225, tvb, offset, -1, PSNAME" RAS");
@@ -11476,7 +11488,7 @@ void proto_register_h225(void) {
         NULL, HFILL }},
 
 /*--- End of included file: packet-h225-hfarr.c ---*/
-#line 812 "./asn1/h225/packet-h225-template.c"
+#line 824 "./asn1/h225/packet-h225-template.c"
   };
 
   /* List of subtrees */
@@ -11726,7 +11738,7 @@ void proto_register_h225(void) {
     &ett_h225_T_result,
 
 /*--- End of included file: packet-h225-ettarr.c ---*/
-#line 818 "./asn1/h225/packet-h225-template.c"
+#line 830 "./asn1/h225/packet-h225-template.c"
   };
 
   static tap_param h225_stat_params[] = {