heap-buffer-overflow in r_readc() at fromswf.c:264

[Marsman1996]

A heap buffer overflow occurs when makeswf parse a invalid swf file, and the filename extension is .swf.

Test Environment

Ubuntu 20.04, 64 bit
libming (master 04aee52)

Steps to reproduce

1. compile libming with ASAN

$ CC="clang -fsanitize=address,fuzzer-no-link -g" CFLAGS+=" -fcommon" ./configure 
$ make

2. Download the poc file from here and run cmd
   $ makeswf $POC

ASAN report

$ ./bin_asan/bin/makeswf ./poc-makeswf-04aee52-r_readc-HBO.swf
Output file name: out.swf
Output compression level: 9
Output SWF version: 6
=================================================================
==5625==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60800000013f at pc 0x0000004f15b5 bp 0x7fff376560d0 sp 0x7fff376560c8
WRITE of size 1 at 0x60800000013f thread T0
    #0 0x4f15b4 in r_readc /opt/disk/marsman/libming/04aee52/build_asan/src/blocks/fromswf.c:264:34
    #1 0x4f1a37 in getbits /opt/disk/marsman/libming/04aee52/build_asan/src/blocks/fromswf.c:143:18
    #2 0x4f1656 in rect /opt/disk/marsman/libming/04aee52/build_asan/src/blocks/fromswf.c:169:9
    #3 0x4efe15 in openswf /opt/disk/marsman/libming/04aee52/build_asan/src/blocks/fromswf.c:303:2
    #4 0x4eedbe in newSWFPrebuiltClip_fromInput /opt/disk/marsman/libming/04aee52/build_asan/src/blocks/fromswf.c:1302:8
    #5 0x4cbea3 in embed_swf /opt/disk/marsman/libming/04aee52/build_asan/util/makeswf.c:699:14
    #6 0x4ca4d9 in main /opt/disk/marsman/libming/04aee52/build_asan/util/makeswf.c:401:4
    #7 0x7f0aa6b3d83f in __libc_start_main /build/glibc-S7Ft5T/glibc-2.23/csu/../csu/libc-start.c:291
    #8 0x41c5a8 in _start (/opt/disk/marsman/libming/04aee52/bin_asan/bin/makeswf+0x41c5a8)

0x60800000013f is located 199 bytes to the right of 88-byte region [0x608000000020,0x608000000078)
allocated by thread T0 here:
    #0 0x4975fd in malloc /local/mnt/workspace/bcain_clang_vm-bcain-aus_3184/final/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:145:3
    #1 0x4ef8d8 in openswf /opt/disk/marsman/libming/04aee52/build_asan/src/blocks/fromswf.c:271:41
    #2 0x4eedbe in newSWFPrebuiltClip_fromInput /opt/disk/marsman/libming/04aee52/build_asan/src/blocks/fromswf.c:1302:8
    #3 0x4cbea3 in embed_swf /opt/disk/marsman/libming/04aee52/build_asan/util/makeswf.c:699:14
    #4 0x4ca4d9 in main /opt/disk/marsman/libming/04aee52/build_asan/util/makeswf.c:401:4
    #5 0x7f0aa6b3d83f in __libc_start_main /build/glibc-S7Ft5T/glibc-2.23/csu/../csu/libc-start.c:291

SUMMARY: AddressSanitizer: heap-buffer-overflow /opt/disk/marsman/libming/04aee52/build_asan/src/blocks/fromswf.c:264:34 in r_readc
Shadow bytes around the buggy address:
  0x0c107fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c107fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c107fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c107fff8000: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 fa
  0x0c107fff8010: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c107fff8020: fa fa fa fa fa fa fa[fa]fa fa fa fa fa fa fa fa
  0x0c107fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c107fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c107fff8050: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c107fff8060: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c107fff8070: 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
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  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
  Shadow gap:              cc
==5625==ABORTING