From 29b90105499d03957a63c0efb22a7852b2b1faa1 Mon Sep 17 00:00:00 2001 From: Guillaume Nault Date: Wed, 7 Nov 2018 19:28:56 +0100 Subject: ipcp: fix uninitialised memory access when negociating *-DNS-Address When handling the EV_DNS event, IPCP assumes that the ->dns1 and ->dns2 fields of the event structure are properly set. But that may not be the case. If only one of the MS-Primary-DNS-Server or MS-Secondary-DNS-Server RADIUS attributes was received, then only ->dns1 or ->dns2 is set, while the other keeps a non initialised value. This uninitialised value is then copied by ev_dns() and proposed to the peer when negociating the Primary-DNS-Address or Secondary-DNS-Address IPCP options. That leaks four bytes of the stack to the network and prevents using the values found in the [dns] section of accel-ppp.conf as fallback. Fix this by initialising the whole event structure in rad_proc_attrs(). Then, in ev_dns(), we can check if ->dns1 or ->dns2 is properly set before copying them. That allows to propery fallback to accel-ppp.conf values when one of the values was not provided by RADIUS. Signed-off-by: Guillaume Nault --- accel-pppd/ppp/ipcp_opt_dns.c | 12 ++++++++---- accel-pppd/radius/radius.c | 3 +-- 2 files changed, 9 insertions(+), 6 deletions(-) (limited to 'accel-pppd') diff --git a/accel-pppd/ppp/ipcp_opt_dns.c b/accel-pppd/ppp/ipcp_opt_dns.c index f4028448..56160fe0 100644 --- a/accel-pppd/ppp/ipcp_opt_dns.c +++ b/accel-pppd/ppp/ipcp_opt_dns.c @@ -151,11 +151,15 @@ static void ev_dns(struct ev_dns_t *ev) ppp = container_of(ev->ses, typeof(*ppp), ses); - dns_opt = container_of(ipcp_find_option(ppp, &dns1_opt_hnd), typeof(*dns_opt), opt); - dns_opt->addr = ev->dns1; + if (ev->dns1) { + dns_opt = container_of(ipcp_find_option(ppp, &dns1_opt_hnd), typeof(*dns_opt), opt); + dns_opt->addr = ev->dns1; + } - dns_opt = container_of(ipcp_find_option(ppp, &dns2_opt_hnd), typeof(*dns_opt), opt); - dns_opt->addr = ev->dns2; + if (ev->dns2) { + dns_opt = container_of(ipcp_find_option(ppp, &dns2_opt_hnd), typeof(*dns_opt), opt); + dns_opt->addr = ev->dns2; + } } static void load_config(void) diff --git a/accel-pppd/radius/radius.c b/accel-pppd/radius/radius.c index 6c3c8ee8..5e8196d5 100644 --- a/accel-pppd/radius/radius.c +++ b/accel-pppd/radius/radius.c @@ -148,14 +148,13 @@ out_err: int rad_proc_attrs(struct rad_req_t *req) { + struct ev_dns_t dns = {}; struct rad_attr_t *attr; struct ipv6db_addr_t *a; - struct ev_dns_t dns; struct ev_wins_t wins; int res = 0; struct radius_pd_t *rpd = req->rpd; - dns.ses = NULL; wins.ses = NULL; req->rpd->acct_interim_interval = conf_acct_interim_interval; -- cgit v1.2.3