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().
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Linux | Linux | 5.19 | 6.0.13 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 6.1.4-1 | — |
| Debian 13 | linux | 6.1.4-1 | — |
| Debian 12 | linux | 6.1.4-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | linux-raspi-realtime | No fix yet | — |
| Ubuntu 22.04 LTS | linux-riscv +32 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-gke +26 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-gcp +13 | No fix yet | — |
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9 | bpftool | 7.0.0-284.11.1.el9_2 | RHSA-2023:2458 |
| RHEL 9 | perf +48 | 5.14.0-284.11.1.el9_2 | RHSA-2023:2458 |
Advisories 2
- WID-SEC-2024-3251 Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service BSI CERT-Bund (WID) · Nov 11, 2026
- RHSA-2023:2458 Red Hat Security Advisory: kernel security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Oct 17, 2026