From: Naveen Albert <asterisk@phreaknet.org>
Date: Tue, 3 May 2022 12:44:07 +0000 (+0000)
Subject: loader: Prevent deadlock using tab completion.
X-Git-Tag: 18.13.0-rc1~17
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=193688dd23d75408beeada1197cb0c15800d0e66;p=thirdparty%2Fasterisk.git

loader: Prevent deadlock using tab completion.

If tab completion using ast_module_helper is attempted
during startup, deadlock will ensue because the CLI
will attempt to lock the module list while it is already
locked by the loader. This causes deadlock because when
the loader tries to acquire the CLI lock, they are blocked
on each other.

Waiting for startup to complete is not feasible because
the CLI lock is acquired while waiting, so deadlock will
ensure regardless of whether or not a lock on the module
list is attempted.

To prevent deadlock, we immediately abort if tab completion
is attempted on the module list before Asterisk is fully
booted.

ASTERISK-30039 #close

Change-Id: Idd468906c512bb196631e366a8f597a0e2e9271d
---

diff --git a/include/asterisk/module.h b/include/asterisk/module.h
index cce8735fc1..f79dc8eb10 100644
--- a/include/asterisk/module.h
+++ b/include/asterisk/module.h
@@ -283,7 +283,7 @@ int ast_loader_unregister(int (*updater)(void));
  * \param type The type of action that will be performed by CLI.
  *
  * \retval A possible completion of the partial match.
- * \retval NULL if no matches were found.
+ * \retval NULL if no matches were found or Asterisk is not yet fully booted.
  */
 char *ast_module_helper(const char *line, const char *word, int pos, int state, int rpos, enum ast_module_helper_type type);
 
diff --git a/main/loader.c b/main/loader.c
index 4c6c2a809e..549e3f0e52 100644
--- a/main/loader.c
+++ b/main/loader.c
@@ -1382,6 +1382,11 @@ char *ast_module_helper(const char *line, const char *word, int pos, int state,
 		return NULL;
 	}
 
+	/* Tab completion can't be used during startup, or CLI and loader will deadlock. */
+	if (!ast_test_flag(&ast_options, AST_OPT_FLAG_FULLY_BOOTED)) {
+		return NULL;
+	}
+
 	if (type == AST_MODULE_HELPER_LOAD) {
 		module_load_helper(word);