AddressSanitizer: heap-buffer-overflow in pspdf_prepare_page(int) ps-pdf.cxx:1440:19

[chibataiki]

Hello, While fuzzing htmldoc , I found a heap-buffer-overflow in the pspdf_prepare_page() ,in ps-pdf.cxx:1440:19

• test platform
  htmldoc Version 1.9.12 git [master 6898d0a]
  OS :Ubuntu 20.04.1 LTS x86_64
  kernel: 5.4.0-53-generic
  compiler: clang version 10.0.0-4ubuntu1

reproduced:

htmldoc -f demo.pdf   poc1.html

poc(zipped for update): poc1.zip

=================================================================
==38053==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x621000002784 at pc 0x00000055eaf5 bp 0x7ffc477b4a50 sp 0x7ffc477b4a48
READ of size 4 at 0x621000002784 thread T0
    #0 0x55eaf4 in pspdf_prepare_page(int) /home/htmldoc_sani/htmldoc/ps-pdf.cxx:1440:19
    #1 0x54fa89 in pspdf_export /home/htmldoc_sani/htmldoc/ps-pdf.cxx:820:7
    #2 0x53c845 in main /home/htmldoc_sani/htmldoc/htmldoc.cxx:1291:3
    #3 0x7fab7bf310b2 in __libc_start_main /build/glibc-eX1tMB/glibc-2.31/csu/../csu/libc-start.c:308:16
    #4 0x41f8bd in _start (/home/htmldoc_sani/htmldoc/htmldoc+0x41f8bd)

0x621000002784 is located 644 bytes to the right of 4096-byte region [0x621000001500,0x621000002500)
freed by thread T0 here:
    #0 0x4ee210 in free /home/work/libfuzzer-workshop/src/llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:124
    #1 0x7fab7bf9eff4 in _IO_setb /build/glibc-eX1tMB/glibc-2.31/libio/genops.c:331:5

previously allocated by thread T0 here:
    #0 0x4ee5df in __interceptor_malloc /home/work/libfuzzer-workshop/src/llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:146
    #1 0x7fab7bf8ee83 in _IO_file_doallocate /build/glibc-eX1tMB/glibc-2.31/libio/filedoalloc.c:101:7

SUMMARY: AddressSanitizer: heap-buffer-overflow /home/htmldoc_sani/htmldoc/ps-pdf.cxx:1440:19 in pspdf_prepare_page(int)
Shadow bytes around the buggy address:
  0x0c427fff84a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c427fff84b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c427fff84c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c427fff84d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c427fff84e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c427fff84f0:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c427fff8500: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c427fff8510: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c427fff8520: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c427fff8530: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c427fff8540: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
==38053==ABORTING

reporter: chiba of topsec alphalab

[michaelrsweet]

Confirmed, investigating...

[michaelrsweet]

Fixed by the changes for #414.

[chibataiki]

CVE-2021-26252 assigned