CVE-2022-45493: Heap Overflow in json.h(json_parse_key())

Heap Overflow in json_parse_key()
In json_parse_key(), there is a heap out-of-bound write. The bug can be triggered with an invocation of json_parse_ex() with specific flags combination. The root cause of this vulnerability is that the parameter string transferred to json_parse_key() is not properly sanitized, and it is pointed to out-of-bound position assigned by upper layer function.

Here is the output of Google ASAN when the vulnerability is triggerred:

The flags is 0xd6d7d6d6247bff7f

==5286==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x61f000000c58 at pc 0x5651b3173086 bp 0x7ffcafde8e10 sp 0x7ffcafde8e08
WRITE of size 8 at 0x61f000000c58 thread T0
#0 0x5651b3173085 in json_parse_key /home/hyrathon/Desktop/jsonh/./json.h:1576:22
#1 0x5651b3174e8b in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1694:11
#2 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#3 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#4 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#5 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#6 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#7 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#8 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#9 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#10 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#11 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#12 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#13 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#14 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#15 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#16 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#17 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#18 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#19 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#20 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#21 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#22 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#23 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#24 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#25 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#26 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#27 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#28 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#29 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#30 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#31 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#32 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#33 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#34 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#35 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#36 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#37 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#38 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#39 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#40 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#41 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#42 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#43 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#44 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#45 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#46 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#47 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#48 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#49 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#50 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#51 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#52 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#53 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#54 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#55 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#56 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#57 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#58 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#59 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#60 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#61 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#62 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#63 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#64 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#65 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#66 0x5651b3176ad9 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1955:7
#67 0x5651b317ad4b in json_parse_array /home/hyrathon/Desktop/jsonh/./json.h:1809:5
#68 0x5651b3176ed5 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1962:7
#69 0x5651b31758f0 in json_parse_object /home/hyrathon/Desktop/jsonh/./json.h:1719:5
#70 0x5651b31761c8 in json_parse_value /home/hyrathon/Desktop/jsonh/./json.h:1940:5
#71 0x5651b317ec85 in json_parse_ex /home/hyrathon/Desktop/jsonh/./json.h:2129:3
#72 0x5651b3195192 in main /home/hyrathon/Desktop/jsonh/fuzz.c:29:5
#73 0x7f1945b88d8f in __libc_start_call_main csu/…/sysdeps/nptl/libc_start_call_main.h:58:16
#74 0x7f1945b88e3f in __libc_start_main csu/…/csu/libc-start.c:392:3
#75 0x5651b30a3314 in _start (/home/hyrathon/Desktop/jsonh/san+0x33314) (BuildId: a0e983e1c9c38a8763824dc5481f79d22fe8c82a)

0x61f000000c58 is located 14 bytes to the right of 3018-byte region [0x61f000000080,0x61f000000c4a)
allocated by thread T0 here:
#0 0x5651b312615e in __interceptor_malloc (/home/hyrathon/Desktop/jsonh/san+0xb615e) (BuildId: a0e983e1c9c38a8763824dc5481f79d22fe8c82a)
#1 0x5651b317df15 in json_parse_ex /home/hyrathon/Desktop/jsonh/./json.h:2088:18
#2 0x5651b3195192 in main /home/hyrathon/Desktop/jsonh/fuzz.c:29:5
#3 0x7f1945b88d8f in __libc_start_call_main csu/…/sysdeps/nptl/libc_start_call_main.h:58:16

SUMMARY: AddressSanitizer: heap-buffer-overflow /home/hyrathon/Desktop/jsonh/./json.h:1576:22 in json_parse_key
Shadow bytes around the buggy address:
0x0c3e7fff8130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c3e7fff8140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c3e7fff8150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c3e7fff8160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c3e7fff8170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c3e7fff8180: 00 00 00 00 00 00 00 00 00 02 fa[fa]fa fa fa fa
0x0c3e7fff8190: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c3e7fff81a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c3e7fff81b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c3e7fff81c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c3e7fff81d0: 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
==5286==ABORTING
The input to trigger this bug is attached. The first 8 bytes are the flags for json_parse_ex() and the rest is the content(src). Please use address sanitizer to reproduce the bug, as non-crash overflow is hard to detect or locate without shadow memory.

Version: latest commit (sheredom/json.h@bdcf2e1)

Also I will attach another input that can trigger similar bug in json_parse_key().
crash-another.zip