From 6d32c2ae28952b5c1d7a24968e488532fcadc51a Mon Sep 17 00:00:00 2001 From: Matt Caswell Date: Fri, 9 Sep 2016 10:53:39 +0100 Subject: [PATCH] Fix a mem leak in NPN handling If a server sent multiple NPN extensions in a single ClientHello then a mem leak can occur. This will only happen where the client has requested NPN in the first place. It does not occur during renegotiation. Therefore the maximum that could be leaked in a single connection with a malicious server is 64k (the maximum size of the ServerHello extensions section). As this is client side, only occurs if NPN has been requested and does not occur during renegotiation this is unlikely to be exploitable. Issue reported by Shi Lei. Reviewed-by: Rich Salz --- ssl/t1_lib.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c index 8c0a20f963..86833d8c98 100644 --- a/ssl/t1_lib.c +++ b/ssl/t1_lib.c @@ -2405,6 +2405,11 @@ static int ssl_scan_serverhello_tlsext(SSL *s, PACKET *pkt, int *al) *al = TLS1_AD_INTERNAL_ERROR; return 0; } + /* + * Could be non-NULL if server has sent multiple NPN extensions in + * a single Serverhello + */ + OPENSSL_free(s->next_proto_negotiated); s->next_proto_negotiated = OPENSSL_malloc(selected_len); if (s->next_proto_negotiated == NULL) { *al = TLS1_AD_INTERNAL_ERROR; -- 2.25.1