Fix silly nil-pointer-dereference bug introduced in commit d5f6f13.

tglsfdc · tglsfdc · commit 5485c99e7f50 · 2016-11-06T11:29:40.000-05:00
Don't fetch record-&gt;xl_info before we've verified that record isn't
NULL.  Per Coverity.

Michael Paquier
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
@@ -7812,7 +7812,6 @@ ReadCheckpointRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr,
 	}
 
 	record = ReadRecord(xlogreader, RecPtr, LOG, true);
-	info = record->xl_info & ~XLR_INFO_MASK;
 
 	if (record == NULL)
 	{
@@ -7855,6 +7854,7 @@ ReadCheckpointRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr,
 		}
 		return NULL;
 	}
+	info = record->xl_info & ~XLR_INFO_MASK;
 	if (info != XLOG_CHECKPOINT_SHUTDOWN &&
 		info != XLOG_CHECKPOINT_ONLINE)
 	{

Original file line number	Diff line number	Diff line change
`@@ -7812,7 +7812,6 @@ ReadCheckpointRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr,`
`7812`	`7812`	`}`
`7813`	`7813`
`7814`	`7814`	`record = ReadRecord(xlogreader, RecPtr, LOG, true);`
`7815`		`- info = record->xl_info & ~XLR_INFO_MASK;`
`7816`	`7815`
`7817`	`7816`	`if (record == NULL)`
`7818`	`7817`	`{`
`@@ -7855,6 +7854,7 @@ ReadCheckpointRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr,`
`7855`	`7854`	`}`
`7856`	`7855`	`return NULL;`
`7857`	`7856`	`}`
	`7857`	`+ info = record->xl_info & ~XLR_INFO_MASK;`
`7858`	`7858`	`if (info != XLOG_CHECKPOINT_SHUTDOWN &&`
`7859`	`7859`	`info != XLOG_CHECKPOINT_ONLINE)`
`7860`	`7860`	`{`