mupdf library use after free

[Marco Grassi <marco.gra () gmail com>]

Hi,

I disclosed a UAF in MuPDF, you can find the reproducer and report here:

http://bugs.ghostscript.com/show_bug.cgi?id=696941

I put a partially symbolicated ASAN report here for reference

Marco

-----

➜  mupdf ./mupdf_debug/build/debug/mupdf-x11 mucrash1.pdf 2>&1 |
asan_symbolize-3.8
warning: broken xref section, proceeding anyway.
=================================================================
==24575==ERROR: AddressSanitizer: heap-use-after-free on address
0x61700000fda8 at pc 0x0000006b0a54 bp 0x7ffcb040dbb0 sp 0x7ffcb040dba8
READ of size 4 at 0x61700000fda8 thread T0
    #0 0x6b0a53 in pdf_load_xref
/media/bob/e4109b52-3574-43a8-b95d-33b3494128de/misc/mupdf/mupdf_debug/source/pdf/pdf-xref.c:1188
    #1 0x6b0a53 in ?? ??:0
    #2 0x6aac73 in pdf_init_document
/media/bob/e4109b52-3574-43a8-b95d-33b3494128de/misc/mupdf/mupdf_debug/source/pdf/pdf-xref.c:1440
    #3 0x6aac73 in ?? ??:0
    #4 0x6ad4ae in pdf_open_document
/media/bob/e4109b52-3574-43a8-b95d-33b3494128de/misc/mupdf/mupdf_debug/source/pdf/pdf-xref.c:2347
    #5 0x6ad4ae in ?? ??:0
    #6 0x5183d2 in fz_open_document
/media/bob/e4109b52-3574-43a8-b95d-33b3494128de/misc/mupdf/mupdf_debug/source/fitz/document.c:129
    #7 0x5183d2 in ?? ??:0
    #8 0x4fbb2b in pdfapp_open_progressive
/media/bob/e4109b52-3574-43a8-b95d-33b3494128de/misc/mupdf/mupdf_debug/platform/x11/pdfapp.c:317
    #9 0x4fbb2b in ?? ??:0
    #10 0x4fb708 in pdfapp_open
/media/bob/e4109b52-3574-43a8-b95d-33b3494128de/misc/mupdf/mupdf_debug/platform/x11/pdfapp.c:213
    #11 0x4fb708 in ?? ??:0
    #12 0x4f01df in main
/media/bob/e4109b52-3574-43a8-b95d-33b3494128de/misc/mupdf/mupdf_debug/platform/x11/x11_main.c:888
    #13 0x4f01df in ?? ??:0
    #14 0x7f6b723ef82f in __libc_start_main
/build/glibc-GKVZIf/glibc-2.23/csu/../csu/libc-start.c:291
    #15 0x7f6b723ef82f in ?? ??:0
    #16 0x41ad98 in _start ??:?
    #17 0x41ad98 in ?? ??:0

0x61700000fda8 is located 296 bytes inside of 768-byte region
[0x61700000fc80,0x61700000ff80)
freed by thread T0 here:
    #0 0x4bad40 in __interceptor_cfree.localalias.0 asan_malloc_linux.cc.o:?
    #1 0x4bad40 in ?? ??:0
    #2 0x516018 in fz_free_default
/media/bob/e4109b52-3574-43a8-b95d-33b3494128de/misc/mupdf/mupdf_debug/source/fitz/memory.c:225
    #3 0x516018 in ?? ??:0

previously allocated by thread T0 here:
    #0 0x4baec8 in malloc ??:?
    #1 0x4baec8 in ?? ??:0
    #2 0x515f68 in fz_malloc_default
/media/bob/e4109b52-3574-43a8-b95d-33b3494128de/misc/mupdf/mupdf_debug/source/fitz/memory.c:213
    #3 0x515f68 in ?? ??:0
    #4 0x6b9aae in pdf_xref_find_subsection
/media/bob/e4109b52-3574-43a8-b95d-33b3494128de/misc/mupdf/mupdf_debug/source/pdf/pdf-xref.c:740
    #5 0x6b9aae in ?? ??:0

SUMMARY: AddressSanitizer: heap-use-after-free
(/media/bob/e4109b52-3574-43a8-b95d-33b3494128de/misc/mupdf/mupdf_debug/build/debug/mupdf-x11+0x6b0a53)
Shadow bytes around the buggy address:
  0x0c2e7fff9f60: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c2e7fff9f70: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c2e7fff9f80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c2e7fff9f90: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c2e7fff9fa0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
=>0x0c2e7fff9fb0: fd fd fd fd fd[fd]fd fd fd fd fd fd fd fd fd fd
  0x0c2e7fff9fc0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c2e7fff9fd0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c2e7fff9fe0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c2e7fff9ff0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c2e7fffa000: 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
==24575==ABORTING