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 2a6637fdda398f0b3d4b1719322bf3fa3ef54672..14d042e220e63d1c8596cb99c69f7277ddcadc90 100644 (file)
--- a/src/interfaces/libpq/fe-misc.c
+++ b/src/interfaces/libpq/fe-misc.c
@@ -1057,7 +1057,7 @@ 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 bbae8eff813906cc97b751677153ee6891e9e4bd..766d4a0b2ce9372dacce43768c2039d3781c66dd 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