CVE-2023-53635

In the Linux kernel, the following vulnerability has been resolved:

netfilter: conntrack: fix wrong ct->timeout value

(struct nf_conn)->timeout is an interval before the conntrack confirmed. After confirmed, it becomes a timestamp.

It is observed that timeout of an unconfirmed conntrack: - Set by calling ctnetlinkchangetimeout(). As a result, nfct_time_stamp was wrongly added to ct->timeout twice. - Get by calling ctnetlinkdumptimeout(). As a result, nfct_time_stamp was wrongly subtracted.

Call Trace: <TASK> dumpstacklvl ctnetlinkdumptimeout __ctnetlinkgluebuild ctnetlinkgluebuild __nfqnlenqueuepacket nfqueue nfhookslow ipmc_output ? __pfxipfinishoutput ipsend_skb ? __pfxdstoutput udpsendskb udp_sendmsg ? __pfxipgenericgetfrag socksendmsg

Separate the 2 cases in: - Setting ct->timeout in _nfctsettimeout(). - Getting ct->timeout in ctnetlinkdumptimeout().

Pablo appends:

Update ctnetlink to set up the timeout after the IPS_CONFIRMED flag is set on, otherwise conntrack creation via ctnetlink breaks.

Note that the problem described in this patch occurs since the introduction of the nfnetlink_queue conntrack support, select a sufficiently old Fixes: tag for -stable kernel to pick up this fix.