libming: listswf: heap-based buffer overflow in _iprintf (outputtxt.c)

Description:
libming is a Flash (SWF) output library. It can be used from PHP, Perl, Ruby, Python, C, C++, Java, and probably more on the way..

A fuzzing revealed an overflow in listswf. The bug does not reside in any shared object but if you have a web application that calls directly the listswf binary to parse untrusted swf, then you are affected.

The complete ASan output:

# listswf $FILE
header indicates a filesize of 18446744072727653119 but filesize is 165
File version: 128
File size: 165
Frame size: (-4671272,-4672424)x(-4703645,4404051)
Frame rate: 142.777344 / sec.
Total frames: 2696

Offset: 25 (0x0019)
Block type: 67 (Unknown Block Type)
Block length: 24


0000: 00 97 6b ba 06 91 6f 98  7a 38 01 00 a6 e3 80 2c    ..k...o. z8.....,
0010: 77 25 d3 d3 1a 19 80 7f                            w%.....



Offset: 51 (0x0033)
Block type: 24 (SWF_PROTECT)
Block length: 1                                                                                                                                                                                
                                                                                                                                                                                               
=================================================================                                                                                                                              
==3132==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60200000eff1 at pc 0x000000499d10 bp 0x7ffc34a55e10 sp 0x7ffc34a555c0                                                       
READ of size 2 at 0x60200000eff1 thread T0                                                                                                                                                     
    #0 0x499d0f in printf_common /tmp/portage/sys-devel/llvm-3.9.0-r1/work/llvm-3.9.0.src/projects/compiler-rt/lib/asan/../sanitizer_common/sanitizer_common_interceptors_format.inc:545       
    #1 0x499a9d in printf_common /tmp/portage/sys-devel/llvm-3.9.0-r1/work/llvm-3.9.0.src/projects/compiler-rt/lib/asan/../sanitizer_common/sanitizer_common_interceptors_format.inc:545       
    #2 0x49abfa in __interceptor_vfprintf /tmp/portage/sys-devel/llvm-3.9.0-r1/work/llvm-3.9.0.src/projects/compiler-rt/lib/asan/../sanitizer_common/sanitizer_common_interceptors.inc:1321    
    #3 0x509dd7 in vprintf /usr/include/bits/stdio.h:38:10                                                                                                                                     
    #4 0x509dd7 in _iprintf /tmp/portage/media-libs/ming-0.4.7/work/ming-0_4_7/util/outputtxt.c:144                                                                                            
    #5 0x51f1f5 in outputSWF_PROTECT /tmp/portage/media-libs/ming-0.4.7/work/ming-0_4_7/util/outputtxt.c:1873:5                                                                                
    #6 0x51c35b in outputBlock /tmp/portage/media-libs/ming-0.4.7/work/ming-0_4_7/util/outputtxt.c:2933:4                                                                                      
    #7 0x527e83 in readMovie /tmp/portage/media-libs/ming-0.4.7/work/ming-0_4_7/util/main.c:277:4                                                                                              
    #8 0x527e83 in main /tmp/portage/media-libs/ming-0.4.7/work/ming-0_4_7/util/main.c:350                                                                                                     
    #9 0x7f0f1ff6861f in __libc_start_main /var/tmp/portage/sys-libs/glibc-2.22-r4/work/glibc-2.22/csu/libc-start.c:289                                                                        
    #10 0x419b38 in _init (/usr/bin/listswf+0x419b38)                                                                                                                                          
                                                                                                                                                                                               
0x60200000eff1 is located 0 bytes to the right of 1-byte region [0x60200000eff0,0x60200000eff1)                                                                                                
allocated by thread T0 here:                                                                                                                                                                   
    #0 0x4d28f8 in malloc /tmp/portage/sys-devel/llvm-3.9.0-r1/work/llvm-3.9.0.src/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:64                                                       
    #1 0x59b9ab in readBytes /tmp/portage/media-libs/ming-0.4.7/work/ming-0_4_7/util/read.c:201:17                                                                                             
    #2 0x592864 in parseSWF_PROTECT /tmp/portage/media-libs/ming-0.4.7/work/ming-0_4_7/util/parser.c:2668:26                                                                                   
    #3 0x5302cb in blockParse /tmp/portage/media-libs/ming-0.4.7/work/ming-0_4_7/util/blocktypes.c:145:14                                                                                      
    #4 0x527d4f in readMovie /tmp/portage/media-libs/ming-0.4.7/work/ming-0_4_7/util/main.c:265:11                                                                                             
    #5 0x527d4f in main /tmp/portage/media-libs/ming-0.4.7/work/ming-0_4_7/util/main.c:350                                                                                                     
    #6 0x7f0f1ff6861f in __libc_start_main /var/tmp/portage/sys-libs/glibc-2.22-r4/work/glibc-2.22/csu/libc-start.c:289                                                                        
                                                                                                                                                                                               
SUMMARY: AddressSanitizer: heap-buffer-overflow /tmp/portage/sys-devel/llvm-3.9.0-r1/work/llvm-3.9.0.src/projects/compiler-rt/lib/asan/../sanitizer_common/sanitizer_common_interceptors_format.inc:545 in printf_common                                                                                                                                                                      
Shadow bytes around the buggy address:
  0x0c047fff9da0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9db0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9dc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9dd0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9de0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c047fff9df0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa[01]fa
  0x0c047fff9e00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e20: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e40: 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
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==3132==ABORTING

Affected version:
0.4.7

Fixed version:
0.4.8

Commit fix:
https://github.com/libming/libming/commit/459fa79d04dcd240996765727a726e5dc5c38f34

Credit:
This bug was discovered by Agostino Sarubbo of Gentoo.

CVE:
CVE-2016-9827

Reproducer:
https://github.com/asarubbo/poc/blob/master/00077-libming-heapoverflow-_iprintf

Timeline:
2016-11-24: bug discovered and reported to upstream
2016-12-01: blog post about the issue
2016-12-05: CVE assigned
2017-01-30: upstream released a patch
2017-04-07: upstream released 0.4.8

Note:
This bug was found with American Fuzzy Lop.

Permalink:

libming: listswf: heap-based buffer overflow in _iprintf (outputtxt.c)

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