Don't leak the startup-packet buffer in ProcessStartupPacket.

This is the first actual leakage bug fix in this patch series.

The amount of memory regained is quite negligible of course.
But we don't want Valgrind whining about this in every session.

Author: Tom Lane <[email protected]>
Discussion: https://postgr.es/m/[email protected]

Author: tglsfdc

src/backend/tcop/backend_startup.c

@@ -492,7 +492,7 @@ static int
 ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
 {
 	int32		len;
-	char	   *buf;
+	char	   *buf = NULL;
 	ProtocolVersion proto;
 	MemoryContext oldcontext;
 
@@ -516,7 +516,7 @@ ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
 		 * scanners, which may be less benign, but it's not really our job to
 		 * notice those.)
 		 */
-		return STATUS_ERROR;
+		goto fail;
 	}
 
 	if (pq_getbytes(((char *) &len) + 1, 3) == EOF)
@@ -526,7 +526,7 @@ ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
 			ereport(COMMERROR,
 					(errcode(ERRCODE_PROTOCOL_VIOLATION),
 					 errmsg("incomplete startup packet")));
-		return STATUS_ERROR;
+		goto fail;
 	}
 
 	len = pg_ntoh32(len);
@@ -538,7 +538,7 @@ ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
 		ereport(COMMERROR,
 				(errcode(ERRCODE_PROTOCOL_VIOLATION),
 				 errmsg("invalid length of startup packet")));
-		return STATUS_ERROR;
+		goto fail;
 	}
 
 	/*
@@ -554,7 +554,7 @@ ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
 		ereport(COMMERROR,
 				(errcode(ERRCODE_PROTOCOL_VIOLATION),
 				 errmsg("incomplete startup packet")));
-		return STATUS_ERROR;
+		goto fail;
 	}
 	pq_endmsgread();
 
@@ -568,7 +568,7 @@ ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
 	{
 		ProcessCancelRequestPacket(port, buf, len);
 		/* Not really an error, but we don't want to proceed further */
-		return STATUS_ERROR;
+		goto fail;
 	}
 
 	if (proto == NEGOTIATE_SSL_CODE && !ssl_done)
@@ -607,14 +607,16 @@ ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
 			ereport(COMMERROR,
 					(errcode_for_socket_access(),
 					 errmsg("failed to send SSL negotiation response: %m")));
-			return STATUS_ERROR;	/* close the connection */
+			goto fail;			/* close the connection */
 		}
 
 #ifdef USE_SSL
 		if (SSLok == 'S' && secure_open_server(port) == -1)
-			return STATUS_ERROR;
+			goto fail;
 #endif
 
+		pfree(buf);
+
 		/*
 		 * At this point we should have no data already buffered.  If we do,
 		 * it was received before we performed the SSL handshake, so it wasn't
@@ -661,14 +663,16 @@ ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
 			ereport(COMMERROR,
 					(errcode_for_socket_access(),
 					 errmsg("failed to send GSSAPI negotiation response: %m")));
-			return STATUS_ERROR;	/* close the connection */
+			goto fail;			/* close the connection */
 		}
 
 #ifdef ENABLE_GSS
 		if (GSSok == 'G' && secure_open_gssapi(port) == -1)
-			return STATUS_ERROR;
+			goto fail;
 #endif
 
+		pfree(buf);
+
 		/*
 		 * At this point we should have no data already buffered.  If we do,
 		 * it was received before we performed the GSS handshake, so it wasn't
@@ -863,7 +867,16 @@ ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
 	 */
 	MemoryContextSwitchTo(oldcontext);
 
+	pfree(buf);
+
 	return STATUS_OK;
+
+fail:
+	/* be tidy, just to avoid Valgrind complaints */
+	if (buf)
+		pfree(buf);
+
+	return STATUS_ERROR;
 }
 
 /*