Sorry, I just realized I made a mistake in this patch by forgetting to
cast the timeout to 64-bit before multiplying by HZ. I'll fix it and
send out another version in a little bit.
Sorry about the unnecessary e-mail traffic.
Thanks,
Jay Elliott
On Wed, Nov 15, 2017 at 3:31 AM, Jay Elliott <jelliott@xxxxxxxxxx> wrote:
> 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@xxxxxxxxxx>
> ---
> 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 de4053d..3a336bb 100644
> --- a/net/netfilter/nf_conntrack_netlink.c
> +++ b/net/netfilter/nf_conntrack_netlink.c
> @@ -1560,9 +1560,11 @@ 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 = 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;
> @@ -1762,6 +1764,7 @@ static int change_seq_adj(struct nf_ct_seqadj *seq,
> 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))
> @@ -1770,7 +1773,10 @@ static int change_seq_adj(struct nf_ct_seqadj *seq,
> if (!cda[CTA_TIMEOUT])
> goto err1;
>
> - ct->timeout = nfct_time_stamp + ntohl(nla_get_be32(cda[CTA_TIMEOUT])) * HZ;
> + timeout = 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]) {
> --
> 1.8.1.4
>
--
To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
