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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: Jay Elliott <jelliott@arista.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Jay Elliott 2017-11-15 15:01:13 -08:00 committed by Pablo Neira Ayuso
parent fbcd253d24
commit 8b1836c4b6
1 changed files with 9 additions and 3 deletions
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12
net/netfilter/nf_conntrack_netlink.c
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@ -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]) {