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 ea4c9d2ee0c567d9a0093dcc65d408e679f6cfee..f8786ebe9c846be2f641a9050377510ee584f779 100644 (file)
--- 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
index f634c99ca601c44dd94719d78f3e7f45ae9faa94..b62b49696985a7d09db9d4f1c8b5205baf83d897 100644 (file)
--- a/src/interfaces/libpq/fe-secure-openssl.c
+++ b/src/interfaces/libpq/fe-secure-openssl.c
@@ -264,7 +264,7 @@ rloop:
 bool
 pgtls_read_pending(PGconn *conn)
 {
-       return SSL_pending(conn->ssl);
+       return SSL_pending(conn->ssl) > 0;
 }
 
 ssize_t