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h225: Fix use after free.
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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>
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@jwzawadzki @AndersBroman
jwzawadzki authored and AndersBroman committed Feb 12, 2018
1 parent 27b571e commit e9376e4
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Showing 2 changed files with 29 additions and 5 deletions.
12 changes: 12 additions & 0 deletions epan/dissectors/asn1/h225/packet-h225-template.c
View file
Expand Up @@ -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"
Expand Down Expand Up @@ -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_)
{
Expand All @@ -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);

Expand Down Expand Up @@ -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");
Expand Down
22 changes: 17 additions & 5 deletions epan/dissectors/packet-h225.c
View file
Expand Up @@ -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"
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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_)
{
Expand All @@ -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);

Expand Down Expand Up @@ -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");
Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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[] = {
Expand Down

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