Description

Out-of-bounds Read in function suggest_trie_walk at spellsuggest.c:1437

vim version

git log
commit 83497f875881973df772cc4cc593766345df6c4a (HEAD -> master, tag: v8.2.5105, origin/master, origin/HEAD)

POC

root@fuzz-vm0-187:/home/fuzz/fuzz/vim/afl/src# ./vim -u NONE -i NONE -n -m -X -Z -e -s -S /mnt/share/max/fuzz/poc/vim/poc_obr1_s.dat -c :qa!
=================================================================
==25892==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffcd478687f at pc 0x000000f6de1a bp 0x7ffcd4781cd0 sp 0x7ffcd4781cc8
READ of size 1 at 0x7ffcd478687f thread T0
    #0 0xf6de19 in suggest_trie_walk /home/fuzz/fuzz/vim/afl/src/spellsuggest.c:1437:20
    #1 0xf6a08d in suggest_try_change /home/fuzz/fuzz/vim/afl/src/spellsuggest.c:1217:2
    #2 0xf61979 in spell_suggest_intern /home/fuzz/fuzz/vim/afl/src/spellsuggest.c:1013:5
    #3 0xf5ce9a in spell_find_suggest /home/fuzz/fuzz/vim/afl/src/spellsuggest.c:888:6
    #4 0xf5879d in spell_suggest /home/fuzz/fuzz/vim/afl/src/spellsuggest.c:554:5
    #5 0xb63f84 in nv_zet /home/fuzz/fuzz/vim/afl/src/normal.c:3007:7
    #6 0xb1f59f in normal_cmd /home/fuzz/fuzz/vim/afl/src/normal.c:939:5
    #7 0x814eee in exec_normal /home/fuzz/fuzz/vim/afl/src/ex_docmd.c:8808:6
    #8 0x814718 in exec_normal_cmd /home/fuzz/fuzz/vim/afl/src/ex_docmd.c:8771:5
    #9 0x8142c9 in ex_normal /home/fuzz/fuzz/vim/afl/src/ex_docmd.c:8689:6
    #10 0x7dd249 in do_one_cmd /home/fuzz/fuzz/vim/afl/src/ex_docmd.c:2570:2
    #11 0x7ca105 in do_cmdline /home/fuzz/fuzz/vim/afl/src/ex_docmd.c:992:17
    #12 0xe58b5e in do_source_ext /home/fuzz/fuzz/vim/afl/src/scriptfile.c:1674:5
    #13 0xe555f6 in do_source /home/fuzz/fuzz/vim/afl/src/scriptfile.c:1801:12
    #14 0xe54f33 in cmd_source /home/fuzz/fuzz/vim/afl/src/scriptfile.c:1174:14
    #15 0xe5463e in ex_source /home/fuzz/fuzz/vim/afl/src/scriptfile.c:1200:2
    #16 0x7dd249 in do_one_cmd /home/fuzz/fuzz/vim/afl/src/ex_docmd.c:2570:2
    #17 0x7ca105 in do_cmdline /home/fuzz/fuzz/vim/afl/src/ex_docmd.c:992:17
    #18 0x7ced81 in do_cmdline_cmd /home/fuzz/fuzz/vim/afl/src/ex_docmd.c:586:12
    #19 0x1422702 in exe_commands /home/fuzz/fuzz/vim/afl/src/main.c:3133:2
    #20 0x141e89b in vim_main2 /home/fuzz/fuzz/vim/afl/src/main.c:780:2
    #21 0x1413dad in main /home/fuzz/fuzz/vim/afl/src/main.c:432:12
    #22 0x7f3842261082 in __libc_start_main /build/glibc-SzIz7B/glibc-2.31/csu/../csu/libc-start.c:308:16
    #23 0x41ea4d in _start (/home/fuzz/fuzz/vim/afl/src/vim+0x41ea4d)

Address 0x7ffcd478687f is located in stack of thread T0 at offset 287 in frame
    #0 0xf69a5f in suggest_try_change /home/fuzz/fuzz/vim/afl/src/spellsuggest.c:1184

  This frame has 1 object(s):
    [32, 286) 'fword' (line 1185) <== Memory access at offset 287 overflows this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow /home/fuzz/fuzz/vim/afl/src/spellsuggest.c:1437:20 in suggest_trie_walk
Shadow bytes around the buggy address:
  0x10001a8e8cb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001a8e8cc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001a8e8cd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001a8e8ce0: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
  0x10001a8e8cf0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x10001a8e8d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00[06]
  0x10001a8e8d10: f3 f3 f3 f3 f3 f3 f3 f3 00 00 00 00 00 00 00 00
  0x10001a8e8d20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001a8e8d30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001a8e8d40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10001a8e8d50: 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
==25892==ABORTING

poc_obr1_s.dat

Impact

This vulnerabilities are capable of crashing software, Modify Memory, and possible remote execution