A stack overflow bug in 2v00

[DawnYang-cn]

Hello!
I am learning AFL-Fuzz recently,and I found a bug in this program
POC is here
Please confirm
Best regards

TestVersion

RELEASE_2V00

Environment

gcc (Ubuntu 5.4.0-6ubuntu1~16.04.10) 5.4.0 20160609
./espruino --test id:000000,sig:11,src:006488+005799,op:splice,rep:2

=================================================================
==20078==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffd3311cff6 at pc 0x7ff8ae25b20b bp 0x7ffd3311cef0 sp 0x7ffd3311c698
READ of size 7 at 0x7ffd3311cff6 thread T0
#0 0x7ff8ae25b20a in __interceptor_strlen (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x7020a)
#1 0x40a88f in jsfNameFromString src/jsflash.c:56
#2 0x40e76b in jsfLoadBootCodeFromFlash src/jsflash.c:738
#3 0x4406f7 in jsiSoftInit src/jsinteractive.c:475
#4 0x441a54 in jsiSemiInit src/jsinteractive.c:804
#5 0x441ac6 in jsiInit src/jsinteractive.c:863
#6 0x4d46cc in run_test targets/linux/main.c:64
#7 0x4d53f2 in main targets/linux/main.c:287
#8 0x7ff8ad91b82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
#9 0x402438 in _start (/home/dawn/esp-asan/Espruino-RELEASE_2V00/espruino+0x402438)

Address 0x7ffd3311cff6 is located in stack of thread T0 at offset 38 in frame
#0 0x40e6b5 in jsfLoadBootCodeFromFlash src/jsflash.c:733

This frame has 1 object(s):
[32, 38) 'filename' <== Memory access at offset 38 overflows this variable
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 ??:0 __interceptor_strlen
Shadow bytes around the buggy address:
0x10002661b9a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x10002661b9b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x10002661b9c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x10002661b9d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x10002661b9e0: 00 00 f1 f1 f1 f1 00 01 f4 f4 f3 f3 f3 f3 00 00
=>0x10002661b9f0: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1[06]f4
0x10002661ba00: f4 f4 f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00
0x10002661ba10: 00 00 00 00 00 00 f1 f1 f1 f1 00 f4 f4 f4 f3 f3
0x10002661ba20: f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x10002661ba30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x10002661ba40: 00 00 00 00 f1 f1 f1 f1 04 f4 f4 f4 f2 f2 f2 f2
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
==20078==ABORTING

WRLAB

[gfwilliams]

Thanks! However I believe this issue was actually fixed in Git Head almost 2 months ago now: 013cb1b#diff-15cd35fa4d782436b42c25bbabcb6052

Perhaps you could try again with that and see if it fixed your problems?

I tried here are it does segfault, but it does so inside jsvShowAllocated which is just a debugging tool used after running tests.

[DawnYang-cn]

I pulled the master branch, it does segfault.But as you say the bug seems not be a critical one.Is this necessary to be fixed, I’ve no idea.
I will keep fuzzing for a while.
Thanks for your reply!