From 40b563b1ea89dabb2b6cd90644908134a0c8eff2 Mon Sep 17 00:00:00 2001 From: Jo-Philipp Wich Date: Fri, 13 Mar 2020 10:37:06 +0100 Subject: [PATCH] ustream-openssl: clear error stack before SSL_read/SSL_write The OpenSSL library uses a global error queue per thread which needs to be cleared prior to calling I/O functions in order to get reliable error results. Failure to do so will lead to stray errors reported by SSL_get_error() when an unrelated connection within the same thread encountered a TLS error since the last SSL_read() or SSL_write() on the current connection. This issue was frequently triggered by Google Chrome which usually initiates simultaneous TLS connections (presumably for protocol support probing) and subsequently closes most of them with a "certificate unknown" TLS error, causing the next SSL_get_error() to report an SSL library error instead of the expected SSL_WANT_READ or SSL_WANT_WRITE error states. Solve this issue by invoking ERR_clear_error() prior to invoking SSL_read() or SSL_write() to ensure that the subsequent SSL_get_error() returns current valid results. Signed-off-by: Jo-Philipp Wich (cherry picked from commit 5e1bc3429cbf9c3be4db65ef5dbf21ea99cf5b95) --- ustream-openssl.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/ustream-openssl.c b/ustream-openssl.c index 1469473..fa99e67 100644 --- a/ustream-openssl.c +++ b/ustream-openssl.c @@ -256,6 +256,8 @@ __hidden enum ssl_conn_status __ustream_ssl_connect(struct ustream_ssl *us) void *ssl = us->ssl; int r; + ERR_clear_error(); + if (us->server) r = SSL_accept(ssl); else @@ -277,7 +279,11 @@ __hidden enum ssl_conn_status __ustream_ssl_connect(struct ustream_ssl *us) __hidden int __ustream_ssl_write(struct ustream_ssl *us, const char *buf, int len) { void *ssl = us->ssl; - int ret = SSL_write(ssl, buf, len); + int ret; + + ERR_clear_error(); + + ret = SSL_write(ssl, buf, len); if (ret < 0) { int err = SSL_get_error(ssl, ret); @@ -293,7 +299,11 @@ __hidden int __ustream_ssl_write(struct ustream_ssl *us, const char *buf, int le __hidden int __ustream_ssl_read(struct ustream_ssl *us, char *buf, int len) { - int ret = SSL_read(us->ssl, buf, len); + int ret; + + ERR_clear_error(); + + ret = SSL_read(us->ssl, buf, len); if (ret < 0) { ret = SSL_get_error(us->ssl, ret); -- 2.25.1