Re: [Tarantool-patches] [PATCH luajit] Limit path length passed to C library loader.

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

Hi, Maksim!
Thanks for the patch!
LGTM, except a few minor nits regarding the commit message and the
comment.

On 16.03.23, Maksim Kokryashkin wrote:
> From: Mike Pall <mike>
> 
> (cherry-picked from commit 90e65514dda3994253c1e3007f63da7ace8f6b7b)
> 
> C library loader uses `dlopen` under the hood, which fails, if

Typo: s/C library loader/The C library loader/

> provided library path is longer than PATH_MAX. PATH_MAX is
> 4096 bytes by default, so a corresponsing check is added to

Typo: s/corresponsing/corresponding/

> `ll_loadfunc`.
> 
> Maxim Kokryashkin:
> * added the description and the test for the problem
> 
> Part of tarantool/tarantool#8069
> ---
> Side note: Still no adequate constants like PATH_MAX...
> Side note: There is no test for successfull loadlib, since
> there is one in the PUC-Rio suite.
> 
> Branch: https://github.com/tarantool/luajit/tree/fckxorg/c-library-path-length
> PR: https://github.com/tarantool/tarantool/pull/8449
> 
>  src/lib_package.c                                   |  7 ++++++-
>  test/tarantool-tests/c-library-path-length.test.lua | 13 +++++++++++++
>  2 files changed, 19 insertions(+), 1 deletion(-)
>  create mode 100644 test/tarantool-tests/c-library-path-length.test.lua
> 
> diff --git a/src/lib_package.c b/src/lib_package.c
> index 8573b9f9..67959a10 100644
> --- a/src/lib_package.c
> +++ b/src/lib_package.c
> @@ -215,7 +215,12 @@ static const char *mksymname(lua_State *L, const char *modname,
>  
>  static int ll_loadfunc(lua_State *L, const char *path, const char *name, int r)
>  {
> -  void **reg = ll_register(L, path);
> +  void **reg;
> +  if (strlen(path) >= 4096) {

Side note: Why don't just use PATH_MAX here? AFAIK, it may be less than
4096 bytes. Just complaining.

> +    lua_pushliteral(L, "path too long");
> +    return PACKAGE_ERR_LIB;
> +  }
> +  reg = ll_register(L, path);
>    if (*reg == NULL) *reg = ll_load(L, path, (*name == '*'));
>    if (*reg == NULL) {
>      return PACKAGE_ERR_LIB;  /* Unable to load library. */
> diff --git a/test/tarantool-tests/c-library-path-length.test.lua b/test/tarantool-tests/c-library-path-length.test.lua
> new file mode 100644
> index 00000000..11dd0cf4
> --- /dev/null
> +++ b/test/tarantool-tests/c-library-path-length.test.lua
> @@ -0,0 +1,13 @@
> +local tap = require('tap')
> +local test = tap.test('c-library-path-length')
> +test:plan(2)
> +
> +-- It doesn't really matter how long that string is, if it is longer than 4096.

Minor: comment line is longer than 66 symbols.

> +local long_path = string.rep('/path', 1024)
> +package.cpath = long_path
> +
> +local res, err = package.loadlib(long_path, 'func')
> +test:ok(res == nil, 'loaded library with a too large path')
> +test:like(err, 'path too long', 'incorrect error')
> +
> +os.exit(test:check() and 0 or 1)
> -- 
> 2.37.1 (Apple Git-137.1)
> 

-- 
Best regards,
Sergey Kaplun