Description

heap based buffer overflow in in vim_regsub_both at regexp.c:2473

Vim Version

git log
commit 1a08a3e2a584889f19b84a27672134649b73da58 (HEAD -> master, tag: v9.0.1429, origin/master, origin/HEAD)

Proof of Concept

./vim -u NONE -i NONE -n -m -X -Z -e -s -S POC_vim_regsub_both -c :qa!
=================================================================
==559305==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60600000bc37 at pc 0x55e89c179cab bp 0x7ffdc3294b40 sp 0x7ffdc3294b30
WRITE of size 1 at 0x60600000bc37 thread T0
    #0 0x55e89c179caa in vim_regsub_both /home/Desktop/Fuzz/vim/src/regexp.c:2473
    #1 0x55e89c258b76 in vim_regsub_multi /home/Desktop/Fuzz/vim/src/regexp.c:1964
    #2 0x55e89bb81212 in ex_substitute /home/Desktop/Fuzz/vim/src/ex_cmds.c:4647
    #3 0x55e89bbf5094 in do_one_cmd /home/Desktop/Fuzz/vim/src/ex_docmd.c:2580
    #4 0x55e89bbf5094 in do_cmdline /home/Desktop/Fuzz/vim/src/ex_docmd.c:993
    #5 0x55e89c2cc655 in do_source_ext /home/Desktop/Fuzz/vim/src/scriptfile.c:1759
    #6 0x55e89c2d321b in cmd_source /home/Desktop/Fuzz/vim/src/scriptfile.c:1233
    #7 0x55e89bbf5094 in do_one_cmd /home/Desktop/Fuzz/vim/src/ex_docmd.c:2580
    #8 0x55e89bbf5094 in do_cmdline /home/Desktop/Fuzz/vim/src/ex_docmd.c:993
    #9 0x55e89c2cc655 in do_source_ext /home/Desktop/Fuzz/vim/src/scriptfile.c:1759
    #10 0x55e89c2d321b in cmd_source /home/Desktop/Fuzz/vim/src/scriptfile.c:1233
    #11 0x55e89bbf5094 in do_one_cmd /home/Desktop/Fuzz/vim/src/ex_docmd.c:2580
    #12 0x55e89bbf5094 in do_cmdline /home/Desktop/Fuzz/vim/src/ex_docmd.c:993
    #13 0x55e89c2cc655 in do_source_ext /home/Desktop/Fuzz/vim/src/scriptfile.c:1759
    #14 0x55e89c2d321b in cmd_source /home/Desktop/Fuzz/vim/src/scriptfile.c:1233
    #15 0x55e89bbf5094 in do_one_cmd /home/Desktop/Fuzz/vim/src/ex_docmd.c:2580
    #16 0x55e89bbf5094 in do_cmdline /home/Desktop/Fuzz/vim/src/ex_docmd.c:993
    #17 0x55e89c2cc655 in do_source_ext /home/Desktop/Fuzz/vim/src/scriptfile.c:1759
    #18 0x55e89c2d321b in cmd_source /home/Desktop/Fuzz/vim/src/scriptfile.c:1233
    #19 0x55e89bbf5094 in do_one_cmd /home/Desktop/Fuzz/vim/src/ex_docmd.c:2580
    #20 0x55e89bbf5094 in do_cmdline /home/Desktop/Fuzz/vim/src/ex_docmd.c:993
    #21 0x55e89c2cc655 in do_source_ext /home/Desktop/Fuzz/vim/src/scriptfile.c:1759
    #22 0x55e89c2d321b in cmd_source /home/Desktop/Fuzz/vim/src/scriptfile.c:1233
    #23 0x55e89bbf5094 in do_one_cmd /home/Desktop/Fuzz/vim/src/ex_docmd.c:2580
    #24 0x55e89bbf5094 in do_cmdline /home/Desktop/Fuzz/vim/src/ex_docmd.c:993
    #25 0x55e89c2cc655 in do_source_ext /home/Desktop/Fuzz/vim/src/scriptfile.c:1759
    #26 0x55e89c2d321b in cmd_source /home/Desktop/Fuzz/vim/src/scriptfile.c:1233
    #27 0x55e89bbf5094 in do_one_cmd /home/Desktop/Fuzz/vim/src/ex_docmd.c:2580
    #28 0x55e89bbf5094 in do_cmdline /home/Desktop/Fuzz/vim/src/ex_docmd.c:993
    #29 0x55e89c2cc655 in do_source_ext /home/Desktop/Fuzz/vim/src/scriptfile.c:1759
    #30 0x55e89c2d321b in cmd_source /home/Desktop/Fuzz/vim/src/scriptfile.c:1233
    #31 0x55e89bbf5094 in do_one_cmd /home/Desktop/Fuzz/vim/src/ex_docmd.c:2580
    #32 0x55e89bbf5094 in do_cmdline /home/Desktop/Fuzz/vim/src/ex_docmd.c:993
    #33 0x55e89c2cc655 in do_source_ext /home/Desktop/Fuzz/vim/src/scriptfile.c:1759
    #34 0x55e89c2d2f20 in do_source /home/Desktop/Fuzz/vim/src/scriptfile.c:1905
    #35 0x55e89c2d2f20 in cmd_source /home/Desktop/Fuzz/vim/src/scriptfile.c:1250
    #36 0x55e89bbf5094 in do_one_cmd /home/Desktop/Fuzz/vim/src/ex_docmd.c:2580
    #37 0x55e89bbf5094 in do_cmdline /home/Desktop/Fuzz/vim/src/ex_docmd.c:993
    #38 0x55e89c92eb91 in exe_commands /home/Desktop/Fuzz/vim/src/main.c:3150
    #39 0x55e89c92eb91 in vim_main2 /home/Desktop/Fuzz/vim/src/main.c:782
    #40 0x55e89b829457 in main /home/Desktop/Fuzz/vim/src/main.c:433
    #41 0x7f3f1299ed8f in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
    #42 0x7f3f1299ee3f in __libc_start_main_impl ../csu/libc-start.c:392
    #43 0x55e89b830104 in _start (/home/Desktop/Fuzz/vim/src/vim+0x19d104)

0x60600000bc37 is located 3 bytes to the right of 52-byte region [0x60600000bc00,0x60600000bc34)
allocated by thread T0 here:
    #0 0x7f3f13438867 in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:145
    #1 0x55e89b83065a in lalloc /home/Desktop/Fuzz/vim/src/alloc.c:246

SUMMARY: AddressSanitizer: heap-buffer-overflow /home/Desktop/Fuzz/vim/src/regexp.c:2473 in vim_regsub_both
Shadow bytes around the buggy address:
  0x0c0c7fff9730: fd fd fd fa fa fa fa fa fd fd fd fd fd fd fd fa
  0x0c0c7fff9740: fa fa fa fa fd fd fd fd fd fd fd fa fa fa fa fa
  0x0c0c7fff9750: fd fd fd fd fd fd fd fa fa fa fa fa fd fd fd fd
  0x0c0c7fff9760: fd fd fd fa fa fa fa fa fd fd fd fd fd fd fd fa
  0x0c0c7fff9770: fa fa fa fa 00 00 00 00 00 00 00 00 fa fa fa fa
=>0x0c0c7fff9780: 00 00 00 00 00 00[04]fa fa fa fa fa fa fa fa fa
  0x0c0c7fff9790: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0c7fff97a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0c7fff97b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0c7fff97c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0c7fff97d0: 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
==559305==ABORTING