Fix misuse of an integer as a bool.

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 4e86f1b16, 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
index b7b53d3a71ca78ee4945b37f608b07fd5e82cf6e..291b627409826ddd86f80611147e98e4cce67eb7 100644 (file)
--- a/src/interfaces/libpq/fe-misc.c
+++ b/src/interfaces/libpq/fe-misc.c
@@ -1064,7 +1064,7 @@ 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
index 0d0a3660f50fef977796f610ac2812d538d30ce0..84eb024d6b95e8a51684470805b3930c6f49ae5e 100644 (file)
--- a/src/interfaces/libpq/fe-secure-openssl.c
+++ b/src/interfaces/libpq/fe-secure-openssl.c
@@ -152,7 +152,7 @@ pgtls_open_client(PGconn *conn)
 bool
 pgtls_read_pending(PGconn *conn)
 {
-       return SSL_pending(conn->ssl);
+       return SSL_pending(conn->ssl) > 0;
 }
 
 /*