From 8427ce4c379ee3774b8a9aca13ca7f4bfb76ba85 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Tue, 21 Feb 2023 20:01:43 +0900 Subject: [PATCH] Fix handling of escape sequences in postgres_fdw.application_name postgres_fdw.application_name relies on MyProcPort to define the data that should be added to escape sequences %u (user name) or %d (database name). However this code could be run in processes that lack a MyProcPort, like an autovacuum process, causing crashes. The code generating the application name is made more flexible with this commit, so as it now generates no data for %u and %d if MyProcPort is missing, and a simple "unknown" if MyProcPort exists, but the expected fields are not set. Reported-by: Alexander Lakhin Author: Kyotaro Horiguchi, Michael Paquier Reviewed-by: Hayato Kuroda, Masahiko Sawada Discussion: https://postgr.es/m/17789-8b31c5a4672b74d9@postgresql.org Backpatch-through: 15 --- contrib/postgres_fdw/option.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/contrib/postgres_fdw/option.c b/contrib/postgres_fdw/option.c index 984e4d168a..d530f7d086 100644 --- a/contrib/postgres_fdw/option.c +++ b/contrib/postgres_fdw/option.c @@ -485,8 +485,6 @@ process_pgfdw_appname(const char *appname) const char *p; StringInfoData buf; - Assert(MyProcPort != NULL); - initStringInfo(&buf); for (p = appname; *p != '\0'; p++) @@ -522,13 +520,29 @@ process_pgfdw_appname(const char *appname) appendStringInfoString(&buf, cluster_name); break; case 'd': - appendStringInfoString(&buf, MyProcPort->database_name); + if (MyProcPort) + { + const char *dbname = MyProcPort->database_name; + + if (dbname) + appendStringInfoString(&buf, dbname); + else + appendStringInfoString(&buf, "[unknown]"); + } break; case 'p': appendStringInfo(&buf, "%d", MyProcPid); break; case 'u': - appendStringInfoString(&buf, MyProcPort->user_name); + if (MyProcPort) + { + const char *username = MyProcPort->user_name; + + if (username) + appendStringInfoString(&buf, username); + else + appendStringInfoString(&buf, "[unknown]"); + } break; default: /* format error - ignore it */