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>

0 files changed, 0 insertions, 0 deletions