[Toybox] Ls row segfault

[enh]

i don't see a crash when i follow your repro steps.

oh, an ASAN=1 toybox catches it:

=================================================================
==113660==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x611000002a70 at pc 0x56168ee299b1 bp 0x7ffff2586180 sp
0x7ffff2586178
READ of size 8 at 0x611000002a70 thread T0
    #0 0x56168ee299b0 in listfiles toys/posix/ls.c:364

0x611000002a70 is located 8 bytes to the right of 232-byte region
[0x611000002980,0x611000002a68)
allocated by thread T0 here:
    #0 0x7f6e6affc330 in __interceptor_malloc
(/lib/x86_64-linux-gnu/libasan.so.5+0xe9330)
    #1 0x56168eddc914 in xmalloc lib/xwrap.c:71
    #2 0x56168ee29505 in listfiles toys/posix/ls.c:315
    #3 0x56168ee293b7 in listfiles toys/posix/ls.c:299
    #4 0x56168ee2b1fe in ls_main toys/posix/ls.c:571
    #5 0x56168ede0be5 in toy_exec_which /tmp/toybox/main.c:170
    #6 0x56168ede0c6c in toy_exec /tmp/toybox/main.c:177
    #7 0x56168ede0cb8 in toybox_main /tmp/toybox/main.c:191
    #8 0x56168ede0be5 in toy_exec_which /tmp/toybox/main.c:170
    #9 0x56168ede0c6c in toy_exec /tmp/toybox/main.c:177
    #10 0x56168ede0cb8 in toybox_main /tmp/toybox/main.c:191
    #11 0x56168edca549 in main /tmp/toybox/main.c:255
    #12 0x7f6e6a93f52a in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: heap-buffer-overflow toys/posix/ls.c:364 in listfiles
Shadow bytes around the buggy address:
  0x0c227fff84f0: 00 00 00 00 00 00 00 00 00 04 fa fa fa fa fa fa
  0x0c227fff8500: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
  0x0c227fff8510: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c227fff8520: 00 05 fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c227fff8530: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c227fff8540: 00 00 00 00 00 00 00 00 00 00 00 00 00 fa[fa]fa
  0x0c227fff8550: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c227fff8560: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c227fff8570: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c227fff8580: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c227fff8590: 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
==113660==ABORTING

On Mon, Nov 11, 2019 at 7:42 AM Denys Nykula <nykula at ukr.net> wrote:
>
> With 81 character wide terminal, toy ls dislikes my etc dir, my home dir
> and most other dirs on my netbook, unless given -1 or -l.
>
> etc=`mktemp -d`; echo $etc; cd $etc
> touch ImageMagick-7 Muttrc dbus-1 drirc.d dropbear fontconfig git group \
> group- lynx.cfg lynx.lss mailcap mime.types mk.conf openssl passwd \
> passwd- profile rc.d resolv.conf rhashrc sasl2 sgml shadow shadow- \
> tmux.conf udev wpa_supplicant.conf xml
> ls
> # Segmentation fault
>
> Ls starts to like the dirs again when I remove some files.
>
> rm udev wpa_supplicant.conf xml
> ls
> # Okay
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