Use snprintf not sprintf in pg_waldump's timestamptz_to_str.

tglsfdc · tglsfdc · commit 5d923eb29bb6 · 2018-06-16T14:45:47.000-04:00
This could only cause an issue if strftime returned a ridiculously long timezone name, which seems unlikely; and it wouldn't qualify as a security problem even then, since pg_waldump (nee pg_xlogdump) is a debug tool not part of the server. But gcc 8 has started issuing warnings about it, so let's use snprintf and be safe. Backpatch to 9.3 where this code was added. Discussion: https://postgr.es/m/21789.1529170195@sss.pgh.pa.us
diff --git a/src/bin/pg_waldump/compat.c b/src/bin/pg_waldump/compat.c
@@ -58,7 +58,8 @@ timestamptz_to_str(TimestampTz dt)
 	strftime(ts, sizeof(ts), "%Y-%m-%d %H:%M:%S", ltime);
 	strftime(zone, sizeof(zone), "%Z", ltime);
 
-	sprintf(buf, "%s.%06d %s", ts, (int) (dt % USECS_PER_SEC), zone);
+	snprintf(buf, sizeof(buf), "%s.%06d %s",
+			 ts, (int) (dt % USECS_PER_SEC), zone);
 
 	return buf;
 }

Original file line number	Diff line number	Diff line change
`@@ -58,7 +58,8 @@ timestamptz_to_str(TimestampTz dt)`
`58`	`58`	`strftime(ts, sizeof(ts), "%Y-%m-%d %H:%M:%S", ltime);`
`59`	`59`	`strftime(zone, sizeof(zone), "%Z", ltime);`
`60`	`60`
`61`		`- sprintf(buf, "%s.%06d %s", ts, (int) (dt % USECS_PER_SEC), zone);`
	`61`	`+ snprintf(buf, sizeof(buf), "%s.%06d %s",`
	`62`	`+ ts, (int) (dt % USECS_PER_SEC), zone);`
`62`	`63`
`63`	`64`	`return buf;`
`64`	`65`	`}`