From bef802ece03f9ae9d52a21f0cf4f1bc2c5a1f8aa Mon Sep 17 00:00:00 2001 From: Jouni Malinen Date: Sun, 1 Nov 2015 18:24:16 +0200 Subject: [PATCH] EAP-pwd server: Fix last fragment length validation All but the last fragment had their length checked against the remaining room in the reassembly buffer. This allowed a suitably constructed last fragment frame to try to add extra data that would go beyond the buffer. The length validation code in wpabuf_put_data() prevents an actual buffer write overflow from occurring, but this results in process termination. (CVE-2015-5314) Signed-off-by: Jouni Malinen --- src/eap_server/eap_server_pwd.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/eap_server/eap_server_pwd.c b/src/eap_server/eap_server_pwd.c index cb83ff7..9f787ab 100644 --- a/src/eap_server/eap_server_pwd.c +++ b/src/eap_server/eap_server_pwd.c @@ -970,7 +970,7 @@ static void eap_pwd_process(struct eap_sm *sm, void *priv, /* * the first and all intermediate fragments have the M bit set */ - if (EAP_PWD_GET_MORE_BIT(lm_exch)) { + if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) { if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) { wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow " "attack detected! (%d+%d > %d)", @@ -981,6 +981,8 @@ static void eap_pwd_process(struct eap_sm *sm, void *priv, } wpabuf_put_data(data->inbuf, pos, len); data->in_frag_pos += len; + } + if (EAP_PWD_GET_MORE_BIT(lm_exch)) { wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment", (int) len); return; @@ -990,8 +992,6 @@ static void eap_pwd_process(struct eap_sm *sm, void *priv, * buffering fragments so that's how we know it's the last) */ if (data->in_frag_pos) { - wpabuf_put_data(data->inbuf, pos, len); - data->in_frag_pos += len; pos = wpabuf_head_u8(data->inbuf); len = data->in_frag_pos; wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes", -- 1.9.1