CVE-2022-48974 netfilter: conntrack: fix using __this_cpu_add in preemptible
A bug in the Linux kernel netfilter conntrack module causes a kernel panic when handling invalid extension data, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2022-48974?
CVE-2022-48974 is a medium-severity denial of service vulnerability in Linux kernel, published on 21 Oct 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
netfilter: conntrack: fix using __this_cpu_add in preemptible
Currently in nf_conntrack_hash_check_insert(), when it fails in nf_ct_ext_valid_pre/post(), NF_CT_STAT_INC() will be called in the preemptible context, a call trace can be triggered:
BUG: using __this_cpu_add() in preemptible [00000000] code: conntrack/1636 caller is nf_conntrack_hash_check_insert+0x45/0x430 [nf_conntrack] Call Trace: <TASK> dump_stack_lvl+0x33/0x46 check_preemption_disabled+0xc3/0xf0 nf_conntrack_hash_check_insert+0x45/0x430 [nf_conntrack] ctnetlink_create_conntrack+0x3cd/0x4e0 [nf_conntrack_netlink] ctnetlink_new_conntrack+0x1c0/0x450 [nf_conntrack_netlink] nfnetlink_rcv_msg+0x277/0x2f0 [nfnetlink] netlink_rcv_skb+0x50/0x100 nfnetlink_rcv+0x65/0x144 [nfnetlink] netlink_unicast+0x1ae/0x290 netlink_sendmsg+0x257/0x4f0 sock_sendmsg+0x5f/0x70
This patch is to fix it by changing to use NF_CT_STAT_INC_ATOMIC() for nf_ct_ext_valid_pre/post() check in nf_conntrack_hash_check_insert(), as well as nf_ct_ext_valid_post() in __nf_conntrack_confirm().
Note that nf_ct_ext_valid_pre() check in __nf_conntrack_confirm() is safe to use NF_CT_STAT_INC(), as it's under local_bh_disable().
Which versions are affected by CVE-2022-48974?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2022-48974?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2022-48974 being exploited?
There is no known exploitation of CVE-2022-48974 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2022-48974, GHSA-g3gx-vxgx-5xvc, UBUNTU-CVE-2022-48974.