CVE-2026-80744: netfilter: nf_tables_offload: suppress WARN_ON_ONCE for ENOMEM in abort path

CVE-2026-80744: netfilter: nf_tables_offload: suppress WARN_ON_ONCE for ENOMEM in abort path

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

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

netfilter: nf_tables_offload: suppress WARN_ON_ONCE for ENOMEM in abort path

In nft_flow_rule_offload_abort(), WARN_ON_ONCE(err) is triggered on every
error during rollback, including -ENOMEM. Memory allocation failures are
expected under low-memory conditions and do not indicate a kernel bug.

Trace for example:
nft_flow_offload_chain() // FLOW_BLOCK_BIND
  nft_flow_block_chain()
    nft_chain_offload_cmd()
      nft_block_offload_cmd()
        ->ndo_setup_tc()
        nsim_setup_tc()
          flow_block_cb_setup_simple()
            flow_block_cb_alloc() // fails to -ENOMEM

The warning was reproduced on the 5.10 stable kernel under memory pressure
via fault injection, but the underlying bug exists in mainline as well,
as demonstrated by the ENOMEM trace above. The following splat was
triggered during nf_tables transaction processing:

WARNING: CPU: 0 PID: 8567 at net/netfilter/nf_tables_offload.c:532 nft_flow_rule_offload_abort net/netfilter/nf_tables_offload.c:532 [inline]
WARNING: CPU: 0 PID: 8567 at net/netfilter/nf_tables_offload.c:532 nft_flow_rule_offload_commit+0x971/0xcd0 net/netfilter/nf_tables_offload.c:591
Modules linked in:
CPU: 0 PID: 8567 Comm: syz-executor.0 Not tainted 5.10.260-syzkaller #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
RIP: 0010:nft_flow_rule_offload_abort net/netfilter/nf_tables_offload.c:532 [inline]
RIP: 0010:nft_flow_rule_offload_commit+0x971/0xcd0 net/netfilter/nf_tables_offload.c:591
Call Trace:
 nf_tables_commit+0x3bd/0x4bd0 net/netfilter/nf_tables_api.c:8604
 nfnetlink_rcv_batch+0xb1e/0x1f20 net/netfilter/nfnetlink.c:509
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:579 [inline]
 nfnetlink_rcv+0x3b3/0x420 net/netfilter/nfnetlink.c:597
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x6cd/0xa00 net/netfilter/af_netlink.c:1340
 netlink_sendmsg+0x906/0xe10 net/netfilter/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:651 [inline]
 __sock_sendmsg+0x155/0x190 net/socket.c:663
 ____sys_sendmsg+0x705/0x870 net/socket.c:2379
 ___sys_sendmsg+0x100/0x170 net/socket.c:2433
 __sys_sendmsg+0xe9/0x1c0 net/socket.c:2462
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x67/0xd1

Change the condition to WARN_ON_ONCE(err && err != -ENOMEM) so that
warnings are only emitted for unexpected errors. This aligns with the
common kernel practice of not warning on -ENOMEM.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

The Linux kernel CVE team has assigned CVE-2026-80744 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.5 with commit 63b48c73ff567bbab1f940d6e8f3f48607077a13 and fixed in 5.10.266 with commit 2319033c4bf8bdb275a9e4e1f7af9bf8a457ad79
	Issue introduced in 5.5 with commit 63b48c73ff567bbab1f940d6e8f3f48607077a13 and fixed in 5.15.217 with commit 6ee3803c22b72508c5baf1e5aecb21301b714be0
	Issue introduced in 5.5 with commit 63b48c73ff567bbab1f940d6e8f3f48607077a13 and fixed in 6.1.184 with commit 09bda4b6df222fd1819e8f188c3a6e90caf546d3
	Issue introduced in 5.5 with commit 63b48c73ff567bbab1f940d6e8f3f48607077a13 and fixed in 6.6.153 with commit 17c132e18ca5d1641ddbaed8d0e6ecfd1d38fa0b
	Issue introduced in 5.5 with commit 63b48c73ff567bbab1f940d6e8f3f48607077a13 and fixed in 6.12.105 with commit 7ce9851be6f2b019e96e105a9de99715aec6deb4
	Issue introduced in 5.5 with commit 63b48c73ff567bbab1f940d6e8f3f48607077a13 and fixed in 6.18.46 with commit 4a923fe60939a194777bc605036ce2147ab00c9d
	Issue introduced in 5.5 with commit 63b48c73ff567bbab1f940d6e8f3f48607077a13 and fixed in 7.1.10 with commit c23620a0fa5b1d80399f894c41a9f78bc29d6235
	Issue introduced in 5.5 with commit 63b48c73ff567bbab1f940d6e8f3f48607077a13 and fixed in 7.2 with commit d02f592064347e0c1e0d84f24941ad338838cc48

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-80744
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/netfilter/nf_tables_offload.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/2319033c4bf8bdb275a9e4e1f7af9bf8a457ad79
	https://git.kernel.org/stable/c/6ee3803c22b72508c5baf1e5aecb21301b714be0
	https://git.kernel.org/stable/c/09bda4b6df222fd1819e8f188c3a6e90caf546d3
	https://git.kernel.org/stable/c/17c132e18ca5d1641ddbaed8d0e6ecfd1d38fa0b
	https://git.kernel.org/stable/c/7ce9851be6f2b019e96e105a9de99715aec6deb4
	https://git.kernel.org/stable/c/4a923fe60939a194777bc605036ce2147ab00c9d
	https://git.kernel.org/stable/c/c23620a0fa5b1d80399f894c41a9f78bc29d6235
	https://git.kernel.org/stable/c/d02f592064347e0c1e0d84f24941ad338838cc48