Fix misuse of an integer as a bool.

tglsfdc · tglsfdc · commit ddf927fb1347 · 2019-05-13T10:53:19.000-04:00
pgtls_read_pending is declared to return bool, but what the underlying SSL_pending function returns is a count of available bytes. This is actually somewhat harmless if we're using C99 bools, but in the back branches it's a live bug: if the available-bytes count happened to be a multiple of 256, it would get converted to a zero char value. On machines where char is signed, counts of 128 and up could misbehave as well. The net effect is that when using SSL, libpq might block waiting for data even though some has already been received. Broken by careless refactoring in commit 4e86f1b, so back-patch to 9.5 where that came in. Per bug #15802 from David Binderman. Discussion: https://postgr.es/m/15802-f0911a97f0346526@postgresql.org
diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c
@@ -1094,7 +1094,7 @@ pqSocketCheck(PGconn *conn, int forRead, int forWrite, time_t end_time)
 
 #ifdef USE_SSL
 	/* Check for SSL library buffering read bytes */
-	if (forRead && conn->ssl_in_use && pgtls_read_pending(conn) > 0)
+	if (forRead && conn->ssl_in_use && pgtls_read_pending(conn))
 	{
 		/* short-circuit the select */
 		return 1;
diff --git a/src/interfaces/libpq/fe-secure-openssl.c b/src/interfaces/libpq/fe-secure-openssl.c
@@ -264,7 +264,7 @@ pgtls_read(PGconn *conn, void *ptr, size_t len)
 bool
 pgtls_read_pending(PGconn *conn)
 {
-	return SSL_pending(conn->ssl);
+	return SSL_pending(conn->ssl) > 0;
 }
 
 ssize_t
