Thread: BUG #17514: Application with embedded SQL crashes when executing EXEC SQL PREPARE
BUG #17514: Application with embedded SQL crashes when executing EXEC SQL PREPARE
From
PG Bug reporting form
Date:
The following bug has been logged on the website: Bug reference: 17514 Logged by: Okano Naoki Email address: okano.naoki@jp.fujitsu.com PostgreSQL version: 12.9 Operating system: RHEL 7 Description: Hi, Application with embedded SQL crashes with segmentation fault if I execute EXEC SQL PREPARE command before executing EXEC SQL CONNECT command (*1). I know that it is the correct operation to execute EXEC SQL CONNECT command first and then execute EXEC SQL PREPARE command. But I expect this wrong operation to result in an error, not a crash. Is it correct that this operation causes the application to crash? Or is it a bug? [Environment] * OS version: RHEL 7 * PostgreSQL version: 12 I checked that PostgreSQL 10 and 14 also occurred a same issue. (*1) Here is an exapmle. int main(void) { EXEC SQL BEGIN DECLARE SECTION; char *connection = "tcp:postgresql://localhost/postgres"; char *user = "user_name"; EXEC SQL END DECLARE SECTION; ECPGdebug(1, stderr); /* Skip a CONNECT command deliberately. */ /* EXEC SQL CONNECT TO :connection USER :user; */ EXEC SQL PREPARE stmt1 FROM "SELECT * FROM pg_database WHERE oid = ?"; return (0); } The following is a backtrace of the coredump. (gdb) bt #0 0x00007f9b4d4da150 in parseInput () from /opt/rh/rh-postgresql12/root/usr//lib64/libpq.so.rh-postgresql12-5 #1 0x00007f9b4d4dc60d in PQgetResult () from /opt/rh/rh-postgresql12/root/usr//lib64/libpq.so.rh-postgresql12-5 #2 0x00007f9b4d4dc8cf in PQexecStart () from /opt/rh/rh-postgresql12/root/usr//lib64/libpq.so.rh-postgresql12-5 #3 0x00007f9b4d4dcb6c in PQprepare () from /opt/rh/rh-postgresql12/root/usr//lib64/libpq.so.rh-postgresql12-5 #4 0x00007f9b4dd01a61 in prepare_common () from /opt/rh/rh-postgresql12/root/usr//lib64/libecpg.so.rh-postgresql12-6 #5 0x00007f9b4dd01fb5 in ECPGprepare () from /opt/rh/rh-postgresql12/root/usr//lib64/libecpg.so.rh-postgresql12-6 #6 0x0000000000400a79 in main () Thanks in advance. Regards, Naoki Okano
Re: BUG #17514: Application with embedded SQL crashes when executing EXEC SQL PREPARE
From
Tom Lane
Date:
PG Bug reporting form <noreply@postgresql.org> writes: > Application with embedded SQL crashes with segmentation fault if I execute > EXEC SQL PREPARE > command before executing EXEC SQL CONNECT command (*1). > I know that it is the correct operation to execute EXEC SQL CONNECT command > first > and then execute EXEC SQL PREPARE command. > But I expect this wrong operation to result in an error, not a crash. We could do something like the attached, perhaps. Having said that, an application that includes no error checks is pretty unlikely to fail gracefully :-(. regards, tom lane diff --git a/src/interfaces/ecpg/ecpglib/connect.c b/src/interfaces/ecpg/ecpglib/connect.c index 8dfcabe3b5..90f2ba9701 100644 --- a/src/interfaces/ecpg/ecpglib/connect.c +++ b/src/interfaces/ecpg/ecpglib/connect.c @@ -40,6 +40,8 @@ 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); /* @@ -78,6 +78,8 @@ 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); /*
RE: BUG #17514: Application with embedded SQL crashes when executing EXEC SQL PREPARE
From
"okano.naoki@fujitsu.com"
Date:
Tom Lane wrote: > We could do something like the attached, perhaps. Having said that, > an application that includes no error checks is pretty unlikely to > fail gracefully :-(. Thank you for replying and creating the patch! I applied this patch to the master branch, and confirmed that the application resulted in an error instead of a crash. As with PREPARE, executing DISCONNECT CURRENT also caused the application to crash, but this patch has fixed that. The patch looks good to me. I agree that applications should consider EXEC SQL PREPARE returning errors. Regards, Naoki Okano
Re: BUG #17514: Application with embedded SQL crashes when executing EXEC SQL PREPARE
From
Tom Lane
Date:
"okano.naoki@fujitsu.com" <okano.naoki@fujitsu.com> writes: > I applied this patch to the master branch, and confirmed that the > application resulted in an error instead of a crash. > As with PREPARE, executing DISCONNECT CURRENT also caused the > application to crash, but this patch has fixed that. > The patch looks good to me. Pushed then, thanks for testing! (Note that this will appear in the August releases, not in this week's 14.4 release.) regards, tom lane