[PATCH 06/12] netfilter: conntrack: clamp timeouts to INT_MAX

[Pablo Neira Ayuso]

From: Jay Elliott <jelli...@arista.com>

When the conntracking code multiplies a timeout by HZ, it can overflow
from positive to negative; this causes it to instantly expire.  To
protect against this the multiplication is done in 64-bit so we can
prevent it from exceeding INT_MAX.

Signed-off-by: Jay Elliott <jelli...@arista.com>
Acked-by: Florian Westphal <f...@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
---
 net/netfilter/nf_conntrack_netlink.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/nf_conntrack_netlink.c 
b/net/netfilter/nf_conntrack_netlink.c
index 59c08997bfdf..66d72a8fa87f 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1566,9 +1566,11 @@ static int ctnetlink_change_helper(struct nf_conn *ct,
 static int ctnetlink_change_timeout(struct nf_conn *ct,
                                    const struct nlattr * const cda[])
 {
-       u_int32_t timeout = ntohl(nla_get_be32(cda[CTA_TIMEOUT]));
+       u64 timeout = (u64)ntohl(nla_get_be32(cda[CTA_TIMEOUT])) * HZ;
 
-       ct->timeout = nfct_time_stamp + timeout * HZ;
+       if (timeout > INT_MAX)
+               timeout = INT_MAX;
+       ct->timeout = nfct_time_stamp + (u32)timeout;
 
        if (test_bit(IPS_DYING_BIT, &ct->status))
                return -ETIME;
@@ -1768,6 +1770,7 @@ ctnetlink_create_conntrack(struct net *net,
        int err = -EINVAL;
        struct nf_conntrack_helper *helper;
        struct nf_conn_tstamp *tstamp;
+       u64 timeout;
 
        ct = nf_conntrack_alloc(net, zone, otuple, rtuple, GFP_ATOMIC);
        if (IS_ERR(ct))
@@ -1776,7 +1779,10 @@ ctnetlink_create_conntrack(struct net *net,
        if (!cda[CTA_TIMEOUT])
                goto err1;
 
-       ct->timeout = nfct_time_stamp + ntohl(nla_get_be32(cda[CTA_TIMEOUT])) * 
HZ;
+       timeout = (u64)ntohl(nla_get_be32(cda[CTA_TIMEOUT])) * HZ;
+       if (timeout > INT_MAX)
+               timeout = INT_MAX;
+       ct->timeout = (u32)timeout + nfct_time_stamp;
 
        rcu_read_lock();
        if (cda[CTA_HELP]) {
-- 
2.11.0