Re: [Tarantool-patches] [PATCH luajit] Prevent sanitizer warnings for lj_tab_new*() and table.new().

[Sergey Kaplun via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Hi, Sergey!
Thanks for the patch!
LGTM, after fixing a few nits below.

On 09.06.26, Sergey Bronnikov wrote:
> From: Mike Pall <mike>
> 
> Reported by Sergey Bronnikov.
> 
> (cherry picked from commit 8f421c81ec6aaae0bcd80e01f4353de200afbbc5)
> 
> The Undefined Behaviour Sanitizer [1] produce a warning because

Typo: s/produce/produces/

> the function `lua_createtable()` takes signed integer arguments,
> but the `lj_tab_new_ah()` was not properly validating or converting
> these signed values before using them in unsigned arithmetic.
> 
> The fix changes the signature of `lj_tab_new_ah()` to accept
> uint32_t directly, and adjusts `lua_createtable()` to cast the
> incoming signed int values to uint32_t before passing them.
> 
> [1]: https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html
> 
> Sergey Bronnikov:
> * added the description and the test for the problem
> 
> Part of tarantool/tarantool#12480
> ---
> Branch: https://github.com/tarantool/luajit/tree/ligurio/lj-1458-ub-lj_tab_new
> 
> Related issues:
> - https://github.com/tarantool/tarantool/issues/12480
> - https://github.com/LuaJIT/LuaJIT/issues/1458
> 
> 
>  src/lj_api.c                                  |  2 +-
>  src/lj_tab.c                                  |  4 +--
>  src/lj_tab.h                                  |  2 +-
>  .../lj-1458-ub-table.new.test.lua             | 30 +++++++++++++++++++
>  4 files changed, 34 insertions(+), 4 deletions(-)
>  create mode 100644 test/tarantool-tests/lj-1458-ub-table.new.test.lua
> 

<snipped>

> diff --git a/test/tarantool-tests/lj-1458-ub-table.new.test.lua b/test/tarantool-tests/lj-1458-ub-table.new.test.lua
> new file mode 100644
> index 00000000..d0cf6ff5
> --- /dev/null
> +++ b/test/tarantool-tests/lj-1458-ub-table.new.test.lua

Typo: s/table.new/table-new/

> @@ -0,0 +1,30 @@
> +local tap = require('tap')
> +
> +-- The test file to demonstrate UBSan warning for `table.new()`
> +-- with a minimal and maximum array and hash parts values.
> +-- See also: https://github.com/LuaJIT/LuaJIT/issues/1458.
> +local test = tap.test('lj-1458-ub-table-new')
> +
> +test:plan(8)

Lets use table_sizes * 2 here.

> +
> +local table_new = require('table.new')
> +
> +local INT_MAX =  2 ^ 31 - 1
> +local INT_MIN = -2 ^ 31
> +
> +local table_sizes = {
> +  { 0, INT_MIN },
> +  { 0, INT_MAX },
> +  { INT_MIN, 0 },
> +  { INT_MAX, 0 },
> +}
> +
> +for _, case in ipairs(table_sizes) do
> +  local apart, hpart = unpack(case)
> +  local ok, err = pcall(table_new, apart, hpart)
> +  local message = ('table.new(%d, %d)'):format(apart, hpart)
> +  test:is(ok, false, message .. ' is failed')

Typo? s/failed/OK/

> +  test:ok(err:match('table overflow'), message .. ' correct error message')
> +end
> +
> +test:done(true)
> -- 
> 2.43.0
> 

-- 
Best regards,
Sergey Kaplun