Incomplete fix of buffer overflow in strcpyext, decompile.c:259

[5hadowblad3]

Hi, there.

There is a buffer overflow in the newest master branch 04aee52 which related to incomplete fix of CVE-2019-9114 mentioned in issue #170.
Here is the reproducing command:

swftophp poc

POC:
overflow-decompiler259-20199114.zip

Here is the reproduce trace reported by ASAN:

==168940==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60300000eeab at pc 0x00000041fa80 bp 0x7ffd66331d40 sp 0x7ffd66331d30
WRITE of size 1 at 0x60300000eeab thread T0
    #0 0x41fa7f in strcpyext ../../util/decompile.c:259
    #1 0x41fa7f in getName ../../util/decompile.c:435
    #2 0x4304b8 in decompileREMOVECLIP ../../util/decompile.c:3108
    #3 0x4304b8 in decompileAction ../../util/decompile.c:3497
    #4 0x44e234 in decompileActions ../../util/decompile.c:3535
    #5 0x44e234 in decompile5Action ../../util/decompile.c:3558
    #6 0x4114d9 in outputSWF_INITACTION ../../util/outputscript.c:1860
    #7 0x402836 in readMovie ../../util/main.c:281
    #8 0x402836 in main ../../util/main.c:354
    #9 0x7fbe6bcd982f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
    #10 0x403b38 in _start (/mnt/data/playground/libming/build/util/swftophp+0x403b38)

0x60300000eeab is located 0 bytes to the right of 27-byte region [0x60300000ee90,0x60300000eeab)
allocated by thread T0 here:
    #0 0x7fbe6c63e662 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x98662)
    #1 0x41f3d0 in getName ../../util/decompile.c:434

SUMMARY: AddressSanitizer: heap-buffer-overflow ../../util/decompile.c:259 strcpyext
Shadow bytes around the buggy address:
  0x0c067fff9d80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9d90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9da0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9db0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9dc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c067fff9dd0: fa fa 00 00 00[03]fa fa 00 00 00 fa fa fa 00 00
  0x0c067fff9de0: 00 fa fa fa 00 00 00 00 fa fa 00 00 00 00 fa fa
  0x0c067fff9df0: 00 00 00 00 fa fa 00 00 00 00 fa fa fd fd fd fd
  0x0c067fff9e00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9e10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9e20: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 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
==168940==ABORTING

[attritionorg]

@5hadowblad3 You mention an incomplete fix, but #170 does not have any indication it was fixed at all?

[5hadowblad3]

@attritionorg I found this bug is reported almost two years ago so I thought there is a patch for this issue.

Anyway, it needs to be confirmed by the developer.