Commit 8b1836c4 authored by Jay Elliott's avatar Jay Elliott Committed by Pablo Neira Ayuso
Browse files

netfilter: conntrack: clamp timeouts to INT_MAX 



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: default avatarJay Elliott <jelliott@arista.com>
Acked-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent fbcd253d

net/netfilter/nf_conntrack_netlink.c

+9 −3
Original line number Diff line number Diff line
@@ -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]) {

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