From fc06cdeb11963e348e9787bb95689f9be064a506 Mon Sep 17 00:00:00 2001 From: tb <> Date: Mon, 15 Mar 2021 15:59:04 +0000 Subject: Don't leave stale sequence numbers behind in ssl3_clear() A TLS client doing session reuse in a certain way could run into a use-after-free. Set the sequence numbers inside ssl3_clear() to make sure this points at valid memory and do the initialization of the record layer a bit earlier so that this works as desired. Additionally, explicitly clear the sequence numbers in ssl3_free() which would have turned the use-after-free into a NULL dereference. Issue reported by Ilya Chipitsine. Fix from jsing This is errata/6.8/017_libssl.patch.sig --- src/lib/libssl/s3_lib.c | 11 ++++++++++- src/lib/libssl/ssl_lib.c | 7 +++---- 2 files changed, 13 insertions(+), 5 deletions(-) diff --git a/src/lib/libssl/s3_lib.c b/src/lib/libssl/s3_lib.c index 91bfb5f3b6..97dd2005c2 100644 --- a/src/lib/libssl/s3_lib.c +++ b/src/lib/libssl/s3_lib.c @@ -1,4 +1,4 @@ -/* $OpenBSD: s3_lib.c,v 1.198 2020/09/17 15:42:14 jsing Exp $ */ +/* $OpenBSD: s3_lib.c,v 1.198.4.1 2021/03/15 15:59:04 tb Exp $ */ /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * @@ -1577,6 +1577,10 @@ ssl3_free(SSL *s) free(S3I(s)->alpn_selected); + /* Clear reference to sequence numbers. */ + tls12_record_layer_clear_read_state(s->internal->rl); + tls12_record_layer_clear_write_state(s->internal->rl); + freezero(S3I(s), sizeof(*S3I(s))); freezero(s->s3, sizeof(*s->s3)); @@ -1649,6 +1653,11 @@ ssl3_clear(SSL *s) s->internal->packet_length = 0; s->version = TLS1_VERSION; + tls12_record_layer_set_read_seq_num(s->internal->rl, + S3I(s)->read_sequence); + tls12_record_layer_set_write_seq_num(s->internal->rl, + S3I(s)->write_sequence); + S3I(s)->hs.state = SSL_ST_BEFORE|((s->server) ? SSL_ST_ACCEPT : SSL_ST_CONNECT); } diff --git a/src/lib/libssl/ssl_lib.c b/src/lib/libssl/ssl_lib.c index 1cf64d1301..d7d3d0c051 100644 --- a/src/lib/libssl/ssl_lib.c +++ b/src/lib/libssl/ssl_lib.c @@ -1,4 +1,4 @@ -/* $OpenBSD: ssl_lib.c,v 1.234.4.1 2021/02/03 07:06:13 tb Exp $ */ +/* $OpenBSD: ssl_lib.c,v 1.234.4.2 2021/03/15 15:59:04 tb Exp $ */ /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * @@ -253,6 +253,8 @@ SSL_new(SSL_CTX *ctx) goto err; if ((s->internal = calloc(1, sizeof(*s->internal))) == NULL) goto err; + if ((s->internal->rl = tls12_record_layer_new()) == NULL) + goto err; s->internal->min_version = ctx->internal->min_version; s->internal->max_version = ctx->internal->max_version; @@ -341,9 +343,6 @@ SSL_new(SSL_CTX *ctx) if (!s->method->internal->ssl_new(s)) goto err; - if ((s->internal->rl = tls12_record_layer_new()) == NULL) - goto err; - s->references = 1; s->server = (ctx->method->internal->ssl_accept == ssl_undefined_function) ? 0 : 1; -- cgit v1.2.3-55-g6feb