This PR mainly fixes a possible integer overflow in `json_append_string()`.
When we use `cjson.encoding()` to encode a string larger than 2GB, at specific
compilation flags, an integer overflow may occur leading to truncation, resulting
in the part of the string larger than 2GB not being encoded.
On the other hand, this overflow doesn't cause any read or write out-of-range or segment fault.
1) using -O0 for lua_cjson (`make LUA_DEBUG=yes`)
In this case, `i` will overflow and leads to truncation.
When `i` reaches `INT_MAX+1` and overflows to INT_MIN, when compared to
len, `i` (1000000..00) is expanded to 64 bits signed integer (1111111.....000000) .
At this point i will be greater than len and jump out of the loop, so `for (i = 0; i < len; i++)`
will loop up to 2^31 times, and the part of larger than 2GB will be truncated.
```asm
`i` => -0x24(%rbp)
<+253>: addl $0x1,-0x24(%rbp) ; overflow if i large than 2^31
<+257>: mov -0x24(%rbp),%eax
<+260>: movslq %eax,%rdx ; move a 32-bit value with sign extension into a 64-bit signed
<+263>: mov -0x20(%rbp),%rax
<+267>: cmp %rax,%rdx ; check `i < len`
<+270>: jb 0x212600 <json_append_string+148>
```
2) using -O2/-O3 for lua_cjson (`make LUA_DEBUG=no`, **the default**)
In this case, because singed integer overflow is an undefined behavior, `i` will not overflow.
`i` will be optimized by the compiler and use 64-bit registers for all subsequent instructions.
```asm
<+180>: add $0x1,%rbx ; Using 64-bit register `rbx` for i++
<+184>: lea 0x1(%rdx),%rsi
<+188>: mov %rsi,0x10(%rbp)
<+192>: mov %al,(%rcx,%rdx,1)
<+195>: cmp %rbx,(%rsp) ; check `i < len`
<+199>: ja 0x20b63a <json_append_string+154>
```
3) using 32bit
Because `strbuf_ensure_empty_length()` preallocates memory of length (len * 6 + 2),
in 32-bit `cjson.encode()` can only handle strings smaller than ((2 ^ 32) - 3 ) / 6.
So 32bit is not affected.
Also change `i` in `strbuf_append_string()` to `size_t`.
Since its second argument `str` is taken from the `char2escape` string array which is never
larger than 6, so `strbuf_append_string()` is not at risk of overflow (the bug was unreachable).
* Fix integer overflows due to using wrong integer size.
* Add assertions / panic when overflow still happens.
* Deletion of dead code to avoid need to maintain it
* Some changes are not because of bugs, but rather paranoia.
* Improve cmsgpack and cjson test coverage.
Co-authored-by: Yossi Gottlieb <yossigo@gmail.com>
cjson calls isinf, but some Solaris versions don't have isinf
even with the attempted fix we have in deps/Makefile.
We can harmlessly include the Redis solarisfixes.h header to
give cjson proper isinf.
Note: cjson has a compile-time setting for using their own defined
isinf, but the Redis definition in solarisfixes.h is more complete.
Fixes antirez#1620
The new cjson has some improvements over our current version including
increased platform compatability, a new resource limit to restrict
decode depth, and better invalid number handling.
One minor change was required to deps/Makefile because this version
of cjson doesn't export itself globally, so we added a quick little
define of -DENABLE_CJSON_GLOBAL.
cjson now has an optional higher performing float parsing interface,
but we are not including it (g_fmt.c, dtoa.c) because it requires
endianness declaration during compile time.
This commit is exactly lua_cjson.c from 2.1.0 with one minor
change of altering the two Lua includes for local search
instead of system-wide importing.
