The following crash due to a use-after-free condition can be observed in an ASAN build of Wireshark (current git master), by feeding a malformed file to tshark ("$ ./tshark -nVxr /path/to/file"):

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==6853==ERROR: AddressSanitizer: heap-use-after-free on address 0x60400009d960 at pc 0x7ff7905dc0fe bp 0x7fff079e9fc0 sp 0x7fff079e9fb8
READ of size 4 at 0x60400009d960 thread T0
    #0 0x7ff7905dc0fd in wtap_optionblock_free wireshark/wiretap/wtap_opttypes.c:161:20
    #1 0x7ff7905d7b58 in wtap_close wireshark/wiretap/wtap.c:1211:4
    #2 0x52a08b in load_cap_file wireshark/tshark.c:3685:3
    #3 0x51e4bc in main wireshark/tshark.c:2213:13

0x60400009d960 is located 16 bytes inside of 40-byte region [0x60400009d950,0x60400009d978)
freed by thread T0 here:
    #0 0x4c1d80 in __interceptor_free llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:30
    #1 0x7ff7905dc32f in wtap_optionblock_free wireshark/wiretap/wtap_opttypes.c:173:9
    #2 0x7ff7905d7b58 in wtap_close wireshark/wiretap/wtap.c:1211:4
    #3 0x52a08b in load_cap_file wireshark/tshark.c:3685:3
    #4 0x51e4bc in main wireshark/tshark.c:2213:13

previously allocated by thread T0 here:
    #0 0x4c2098 in malloc llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:40
    #1 0x7ff77bc84610 in g_malloc (/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x4e610)
    #2 0x7ff79055907d in pcapng_read wireshark/wiretap/pcapng.c:2564:35
    #3 0x7ff7905d825b in wtap_read wireshark/wiretap/wtap.c:1253:7
    #4 0x528036 in load_cap_file wireshark/tshark.c:3499:12
    #5 0x51e4bc in main wireshark/tshark.c:2213:13

SUMMARY: AddressSanitizer: heap-use-after-free wireshark/wiretap/wtap_opttypes.c:161:20 in wtap_optionblock_free
Shadow bytes around the buggy address:
  0x0c088000bad0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c088000bae0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c088000baf0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c088000bb00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c088000bb10: fa fa fa fa fa fa fa fa fa fa 00 00 00 00 00 fa
=>0x0c088000bb20: fa fa 00 00 00 00 00 fa fa fa fd fd[fd]fd fd fa
  0x0c088000bb30: fa fa 00 00 00 00 00 fa fa fa 00 00 00 00 00 fa
  0x0c088000bb40: fa fa 00 00 00 00 00 fa fa fa 00 00 00 00 00 fa
  0x0c088000bb50: fa fa 00 00 00 00 00 fa fa fa 00 00 00 00 00 fa
  0x0c088000bb60: fa fa fd fd fd fd fd fd fa fa 00 00 00 00 00 fa
  0x0c088000bb70: fa fa fd fd fd fd fd fa fa fa 00 00 00 00 00 fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Heap right redzone:      fb
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack partial redzone:   f4
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==6853==ABORTING
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The crash was reported at https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=12173. Attached are three files which trigger the crash.

This bug is subject to a 90 day disclosure deadline. If 90 days elapse without a broadly available patch, then the bug report will automatically become visible to the public.
 

asan_heap-uaf_7f3e1f14f0fe_7710_ce9ae4f56c111f4d1f55bd5956899e86.pcap 104 bytes Download

asan_heap-uaf_7f92b97650fe_7710_ce9ae4f56c111f4d1f55bd5956899e86.pcap 104 bytes Download

asan_heap-uaf_7f439e2c90fe_7710_ce9ae4f56c111f4d1f55bd5956899e86.pcap 104 bytes Download