Recently I've encountered a strange crash while calling elog(ERROR, "...")
after the WaitForBackgroundWorkerShutdown() function. It turns out that
_returns_ inside the PG_TRY()..PG_CATCH() block are *highly* undesirable,
since they leave PG_exception_stack pointing to a local struct in a dead
frame, which is an obvious UB. I've attached a patch which fixes this behavior
in the aforementioned function, but there might be more errors like that
elsewhere.
--
Dmitry Ivanov
Postgres Professional: http://www.postgrespro.com
Russian Postgres Company
diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c
index 76619e9..5ecb55a 100644
--- a/src/backend/postmaster/bgworker.c
+++ b/src/backend/postmaster/bgworker.c
@@ -1025,13 +1025,14 @@ WaitForBackgroundWorkerShutdown(BackgroundWorkerHandle *handle)
status = GetBackgroundWorkerPid(handle, &pid);
if (status == BGWH_STOPPED)
- return status;
+ break;
rc = WaitLatch(&MyProc->procLatch,
WL_LATCH_SET | WL_POSTMASTER_DEATH, 0);
if (rc & WL_POSTMASTER_DEATH)
- return BGWH_POSTMASTER_DIED;
+ status = BGWH_POSTMASTER_DIED;
+ break;
ResetLatch(&MyProc->procLatch);
}
--
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