heap-buffer-overflow at Jsi_DSAppendLen src/jsiDString.c:109

[kvenux]

Build environment:

Ubuntu 16.04
gcc 5.4.0
version: 17c32ef
build command:
export JSI__SANITIZE=1
make
test command: ./jsish poc

POC

jsish-1021-000022.txt

Description

Below is the ASAN outputs.

=================================================================
==139092==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60200000a694 at pc 0x7f881c593935 bp 0x7ffeee682e00 sp 0x7ffeee6825a8
READ of size 5 at 0x60200000a694 thread T0
#0 0x7f881c593934 in __asan_memcpy (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x8c934)
#1 0x5c18de in memcpy /usr/include/x86_64-linux-gnu/bits/string3.h:53
#2 0x5c18de in Jsi_DSAppendLen src/jsiDString.c:109
#3 0x5ecbb3 in Jsi_UtfSubstr src/jsiUtf8.c:130
#4 0x4e2180 in StringSubstrCmd src/jsiString.c:145
#5 0x4c4f20 in jsi_FuncCallSub src/jsiProto.c:244
#6 0x73e470 in jsiFunctionSubCall src/jsiEval.c:793
#7 0x73e470 in jsiEvalFunction src/jsiEval.c:828
#8 0x73e470 in jsiEvalCodeSub src/jsiEval.c:1253
#9 0x7509a7 in jsi_evalcode src/jsiEval.c:2188
#10 0x4c5eed in jsi_FuncCallSub src/jsiProto.c:220
#11 0x73e07c in jsiFunctionSubCall src/jsiEval.c:793
#12 0x73e07c in jsiEvalFunction src/jsiEval.c:828
#13 0x73e07c in jsiEvalCodeSub src/jsiEval.c:1253
#14 0x7509a7 in jsi_evalcode src/jsiEval.c:2188
#15 0x7534fb in jsi_evalStrFile src/jsiEval.c:2494
#16 0x49ae7e in Jsi_Main src/jsiInterp.c:917
#17 0xc07b32 in jsi_main src/main.c:44
#18 0x7f881ba3383f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2083f)
#19 0x434fc8 in _start (/home/keven/Fuzzing/jsish-1021/jsish+0x434fc8)

0x60200000a694 is located 0 bytes to the right of 4-byte region [0x60200000a690,0x60200000a694)
allocated by thread T0 here:
#0 0x7f881c59f602 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x98602)
#1 0x49f4b2 in Jsi_Malloc src/jsiUtils.c:52

SUMMARY: AddressSanitizer: heap-buffer-overflow ??:0 __asan_memcpy
Shadow bytes around the buggy address:
0x0c047fff9480: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9490: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff94a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff94b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff94c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c047fff94d0: fa fa[04]fa fa fa 00 fa fa fa 00 fa fa fa 00 fa
0x0c047fff94e0: fa fa 00 fa fa fa 00 fa fa fa 00 fa fa fa 00 fa
0x0c047fff94f0: fa fa 00 fa fa fa 00 fa fa fa 00 fa fa fa 00 fa
0x0c047fff9500: fa fa 00 fa fa fa 00 00 fa fa 00 00 fa fa 00 fa
0x0c047fff9510: fa fa 00 00 fa fa 00 00 fa fa 00 fa fa fa 00 00
0x0c047fff9520: fa fa 00 00 fa fa 00 fa fa fa 00 00 fa fa 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
==139092==ABORTING

[pcmacdon]

Yech, UTF. I've fixed the crash, but can't guarantee it's correct. I need to review UTF support sometime in the future.

FYI, I made the following test script change to let it complete:

--- /tmp/t22.jsi 2020-10-22 12:07:02.974697870 -0700
+++ /tmp/t22_new.txt 2020-10-22 11:52:10.222922772 -0700
@@ -44,7 +44,7 @@
return ''' + escape(String.fromCharCode(charCode)) + ''';
return ''' + expected + ''';
}
-function testIDNCharacter(charCode, expected, expectedNotFirstCharacter) {
+function testIDNCharacter(charCode, expected, expectedNotFirstCharacter='') {
if (expectedNotFirstCharacter == null)
expectedNotFirstCharacter = expected;
}
@@ -202,4 +202,5 @@
testIDNCharacter(65377, 'does not encode', '.');
testIDNCharacter(65279, 'does not encode', '');
}
-successfullyParsed = true;
+var successfullyParsed = true;
+