Avoid ecpglib core dump with out-of-order operations.

tglsfdc · tglsfdc · commit ba412c905af1 · 2022-06-14T18:16:46.000-04:00
If an application executed operations like EXEC SQL PREPARE without having first established a database connection, it could get a core dump instead of the expected clean failure. This occurred because we did "pthread_getspecific(actual_connection_key)" without ever having initialized the TSD key actual_connection_key. The results of that are probably platform-specific, but at least on Linux it often leads to a crash. To fix, add calls to ecpg_pthreads_init() in the code paths that might use actual_connection_key uninitialized. It's harmless (and hopefully inexpensive) to do that more than once. Per bug #17514 from Okano Naoki. The problem's ancient, so back-patch to all supported branches. Discussion: https://postgr.es/m/17514-edd4fad547c5692c@postgresql.org
diff --git a/src/interfaces/ecpg/ecpglib/connect.c b/src/interfaces/ecpg/ecpglib/connect.c
@@ -40,15 +40,16 @@ ecpg_get_connection_nr(const char *connection_name)
 	if ((connection_name == NULL) || (strcmp(connection_name, "CURRENT") == 0))
 	{
 #ifdef ENABLE_THREAD_SAFETY
+		ecpg_pthreads_init();	/* ensure actual_connection_key is valid */
+
 		ret = pthread_getspecific(actual_connection_key);
 
 		/*
 		 * if no connection in TSD for this thread, get the global default
 		 * connection and hope the user knows what they're doing (i.e. using
 		 * their own mutex to protect that connection from concurrent accesses
 		 */
-		/* if !ret then  we  got the connection from TSD */
-		if (NULL == ret)
+		if (ret == NULL)
 			/* no TSD connection, going for global */
 			ret = actual_connection;
 #else
@@ -78,15 +79,16 @@ ecpg_get_connection(const char *connection_name)
 	if ((connection_name == NULL) || (strcmp(connection_name, "CURRENT") == 0))
 	{
 #ifdef ENABLE_THREAD_SAFETY
+		ecpg_pthreads_init();	/* ensure actual_connection_key is valid */
+
 		ret = pthread_getspecific(actual_connection_key);
 
 		/*
 		 * if no connection in TSD for this thread, get the global default
 		 * connection and hope the user knows what they're doing (i.e. using
 		 * their own mutex to protect that connection from concurrent accesses
 		 */
-		/* if !ret then  we  got the connection from TSD */
-		if (NULL == ret)
+		if (ret == NULL)
 			/* no TSD connection here either, using global */
 			ret = actual_connection;
 #else
