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

[Maksim Kokryashkin]

From: Mike Pall <mike>

(cherry-picked from commit 90e65514dda3994253c1e3007f63da7ace8f6b7b)

C library loader uses `dlopen` under the hood, which fails, if
provided library path is longer than PATH_MAX. PATH_MAX is
4096 bytes by default, so a corresponsing check is added to
`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) {
+    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.
+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)