From c5590a6821e37f3b29735f55eb0c2b9c0924138c Mon Sep 17 00:00:00 2001 From: Steffan Karger Date: Thu, 20 Nov 2014 13:43:05 +0100 Subject: Drop too-short control channel packets instead of asserting out. This fixes a denial-of-service vulnerability where an authenticated client could stop the server by triggering a server-side ASSERT(). OpenVPN would previously ASSERT() that control channel packets have a payload of at least 4 bytes. An authenticated client could trigger this assert by sending a too-short control channel packet to the server. Thanks to Dragana Damjanovic for reporting the issue. This bug has been assigned CVE-2014-8104. Signed-off-by: Steffan Karger Acked-by: Gert Doering Message-Id: <1CED409804E2164C8104F9E623B08B9018803B0FE7@FOXDFT02.FOX.local> Signed-off-by: Gert Doering --- src/openvpn/ssl.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'src') diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c index 2adfa26..cdc8eb1 100644 --- a/src/openvpn/ssl.c +++ b/src/openvpn/ssl.c @@ -2036,7 +2036,11 @@ key_method_2_read (struct buffer *buf, struct tls_multi *multi, struct tls_sessi ASSERT (session->opt->key_method == 2); /* discard leading uint32 */ - ASSERT (buf_advance (buf, 4)); + if (!buf_advance (buf, 4)) { + msg (D_TLS_ERRORS, "TLS ERROR: Plaintext buffer too short (%d bytes).", + buf->len); + goto error; + } /* get key method */ key_method_flags = buf_read_u8 (buf); -- cgit