From: Fujii Masao <fujii@postgresql.org>
Date: Fri, 3 Apr 2015 09:29:38 +0000 (+0900)
Subject: Rework handling of OOM when allocating record buffer in XLOG reader.
X-Git-Tag: REL9_5_ALPHA1~498
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9b8d478;p=postgresql

Rework handling of OOM when allocating record buffer in XLOG reader.

Commit 2c03216 changed allocate_recordbuf() so that it uses a palloc to
allocate the read buffer and fails immediately when an out-of-memory error
shows up, even though its callers still expect that NULL is returned in that
case. This bug is fixed making allocate_recordbuf() use a palloc_extended
with MCXT_ALLOC_NO_OOM flag and return NULL in OOM case.

Michael Paquier
---

diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index ba7dfcc028..ffdc9753ad 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -146,7 +146,13 @@ allocate_recordbuf(XLogReaderState *state, uint32 reclength)
 
 	if (state->readRecordBuf)
 		pfree(state->readRecordBuf);
-	state->readRecordBuf = (char *) palloc(newSize);
+	state->readRecordBuf =
+		(char *) palloc_extended(newSize, MCXT_ALLOC_NO_OOM);
+	if (state->readRecordBuf == NULL)
+	{
+		state->readRecordBufSize = 0;
+		return false;
+	}
 	state->readRecordBufSize = newSize;
 	return true;
 }