Modules must have execute permissions to load

Former-commit-id: a4efcd35af

src/module.cpp

@@ -32,6 +32,7 @@
 #include <dlfcn.h>
 #include <mutex>
 #include <condition_variable>
+#include <sys/stat.h>
 
 #define REDISMODULE_CORE 1
 #include "redismodule.h"
@@ -5226,6 +5227,15 @@ int moduleLoad(const char *path, void **module_argv, int module_argc) {
     int (*onload)(void *, void **, int);
     void *handle;
     RedisModuleCtx ctx = REDISMODULE_CTX_INIT;
+    
+    struct stat st;
+    if (stat(path, &st) == 0)
+    {   // this check is best effort
+        if (!(st.st_mode & S_IEXEC)) {
+            serverLog(LL_WARNING, "Module %s failed to load: It does not have execute permissions.", path);
+            return C_ERR;
+        }
+    }
 
     handle = dlopen(path,RTLD_NOW|RTLD_LOCAL);
     if (handle == NULL) {