From 18914f24ec6e704e81a5528cf09f3d54b23ef12b Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Thu, 19 Aug 2021 04:59:06 -0700 Subject: [PATCH] Unset MyBEEntry, making elog.c's call to pgstat_get_my_query_id() safe. Previously log messages late during shutdown could end up using either another backend's PgBackendStatus (multi user) or segfault (single user) because pgstat_get_my_query_id()'s check for !MyBEEntry didn't filter out use after pgstat_beshutdown_hook(). This became a bug in 4f0b0966c86, but was a bit fishy before. But given there's no known problematic cases before 14, it doesn't seem worth backpatching further. Also fixes a wrong filename in a comment, introduced in e1025044. Reported-By: Andres Freund Reviewed-By: Julien Rouhaud Discussion: https://postgr.es/m/Julien Rouhaud Backpatch: 14- --- src/backend/utils/activity/backend_status.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/backend/utils/activity/backend_status.c b/src/backend/utils/activity/backend_status.c index 2901f9f5a9..e19c4506ef 100644 --- a/src/backend/utils/activity/backend_status.c +++ b/src/backend/utils/activity/backend_status.c @@ -46,7 +46,7 @@ bool pgstat_track_activities = false; int pgstat_track_activity_query_size = 1024; -/* exposed so that progress.c can access it */ +/* exposed so that backend_progress.c can access it */ PgBackendStatus *MyBEEntry = NULL; @@ -469,6 +469,9 @@ pgstat_beshutdown_hook(int code, Datum arg) beentry->st_procpid = 0; /* mark invalid */ PGSTAT_END_WRITE_ACTIVITY(beentry); + + /* so that functions can check if backend_status.c is up via MyBEEntry */ + MyBEEntry = NULL; } /*