From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 7 Aug 2018 20:00:44 +0000 (-0400)
Subject: Fix incorrect initialization of BackendActivityBuffer.
X-Git-Tag: REL_11_BETA4~137
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1b5438ec2a4ddb2bc632916efc1ec89f593dac06;p=postgresql

Fix incorrect initialization of BackendActivityBuffer.

Since commit c8e8b5a6e, this has been zeroed out using the wrong length.
In practice the length would always be too small, leading to not zeroing
the whole buffer rather than clobbering additional memory; and that's
pretty harmless, both because shmem would likely start out as zeroes
and because we'd reinitialize any given entry before use.  Still,
it's bogus, so fix it.

Reported by Petru-Florin Mihancea (bug #15312)

Discussion: https://postgr.es/m/153363913073.1303.6518849192351268091@wrigleys.postgresql.org
---

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 084573e77c..10e7acce84 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -2695,7 +2695,7 @@ CreateSharedBackendStatus(void)
 
 	if (!found)
 	{
-		MemSet(BackendActivityBuffer, 0, size);
+		MemSet(BackendActivityBuffer, 0, BackendActivityBufferSize);
 
 		/* Initialize st_activity pointers. */
 		buffer = BackendActivityBuffer;