Fix undefined behaviour in phpdbg_load_module_or_extension

If zend_register_module_ex were to return NULL, then module_entry will
be set to NULL, and the if's body will load module_entry->name. Since
module_entry is NULL, loading the name would cause a NULL pointer
dereference. However, since a NULL pointer dereference is undefined
behaviour, the compiler is free to remove the check.
Fix it by using *name instead of module_entry->name.

Closes GH-10157

Signed-off-by: George Peter Banyard <girgias@php.net>

Author: nielsdos

NEWS

@@ -17,6 +17,9 @@ PHP                                                                        NEWS
   . Fix inverted bailout value in zend_runtime_jit() (Max Kellermann).
   . Fix access to uninitialized variable in accel_preload(). (nielsdos)
 
+- PHPDBG:
+  . Fix undefined behaviour in phpdbg_load_module_or_extension(). (nielsdos)
+
 - TSRM:
   . Fixed Windows shmget() wrt. IPC_PRIVATE. (Tyson Andre)
 

sapi/phpdbg/phpdbg_prompt.c

@@ -1321,7 +1321,7 @@ PHPDBG_API const char *phpdbg_load_module_or_extension(char **path, const char *
 		module_entry->handle = handle;
 
 		if ((module_entry = zend_register_module_ex(module_entry)) == NULL) {
-			phpdbg_error("Unable to register module %s", module_entry->name);
+			phpdbg_error("Unable to register module %s", *name);
 
 			goto quit;
 		}