Clarify that SSL_shutdown() must not be called after a fatal error

Follow on from CVE-2019-1559

Reviewed-by: Richard Levitte <levitte@openssl.org>

diff --git a/doc/man3/SSL_get_error.pod b/doc/man3/SSL_get_error.pod
index a8dd7c10ff78fe74dbe50a44727927418e9ccc0c..5a7a4b7058efe935a1f38aa8d993e345f7adadea 100644 (file)
--- a/doc/man3/SSL_get_error.pod
+++ b/doc/man3/SSL_get_error.pod
@@ -138,17 +138,20 @@ Details depend on the application.
 
 =item SSL_ERROR_SYSCALL
 
-Some non-recoverable I/O error occurred.
-The OpenSSL error queue may contain more information on the error.
-For socket I/O on Unix systems, consult B<errno> for details.
+Some non-recoverable, fatal I/O error occurred. The OpenSSL error queue may
+contain more information on the error. For socket I/O on Unix systems, consult
+B<errno> for details. If this error occurs then no further I/O operations should
+be performed on the connection and SSL_shutdown() must not be called.
 
 This value can also be returned for other errors, check the error queue for
 details.
 
 =item SSL_ERROR_SSL
 
-A failure in the SSL library occurred, usually a protocol error.  The
-OpenSSL error queue contains more information on the error.
+A non-recoverable, fatal error in the SSL library occurred, usually a protocol
+error.  The OpenSSL error queue contains more information on the error. If this
+error occurs then no further I/O operations should be performed on the
+connection and SSL_shutdown() must not be called.
 
 =back
 

diff --git a/doc/man3/SSL_shutdown.pod b/doc/man3/SSL_shutdown.pod
index 0a3d6d370d8b0f2261122d06539090dc4585bed2..551fff6308b6e221ede761b6c08a8b7e099d243e 100644 (file)
--- a/doc/man3/SSL_shutdown.pod
+++ b/doc/man3/SSL_shutdown.pod
@@ -22,6 +22,10 @@ Whether the operation succeeds or not, the SSL_SENT_SHUTDOWN flag is set and
 a currently open session is considered closed and good and will be kept in the
 session cache for further reuse.
 
+Note that SSL_shutdown() must not be called if a previous fatal error has
+occurred on a connection i.e. if SSL_get_error() has returned SSL_ERROR_SYSCALL
+or SSL_ERROR_SSL.
+
 The shutdown procedure consists of two steps: sending of the close_notify
 shutdown alert, and reception of the peer's close_notify shutdown alert.
 The order of those two steps depends on the application.