From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C8C4E516159 for ; Thu, 17 Sep 2026 16:21:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789662093; cv=none; b=HmvqH7x1qWjc8kpH+41azLzYZrOaVR99eaLpcEFrJWkYVRm/EN4LYy1RvCXDsHJsRvPNHqq4It4O2Fj75Iq65Xx5MfX6gefqaGkox7xGF6QT5i9cHwwhR+u9j4ITue5WDj0Q3v3nxveknnGr7kUeo3vBv3+9xng5yCsfe8nLqAg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789662093; c=relaxed/simple; bh=zeMF7s20IeNFxeQ/XBlQVwR0IwLQRN1HJhvOqVoAnyw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=DJA5UFFACmFv5Cly8oixmk4/7OR/Hy6/jKMLWYbPJTtUq+XMmhRWDlmh4TfEOP4+W8TplKwLrSWookB7voimmy4saj0nJUx4ymaxqgLA781/9JKfGVg8n1v1eegxNBt5N2NGjIl0KuihQDM7wmHRbq7sUp8jTpZpKWfK/njvNnU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=L2EvnImw; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="L2EvnImw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2878E1F000FF; Thu, 17 Sep 2026 16:21:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789662091; bh=ixrVUpUJenuZqo2OFMNJ4k75KO1kjJS9w4b6ZP6DWwA=; h=From:To:Cc:Subject:Date:Reply-To; b=L2EvnImw5TBEq/B6r7/cvclYEJosHaVnB3gEYWEIVZJdtFRDHRHpZrDMCpIznQ2pM CYLq/pDM/egFcVR4hSv8YKk0x0kZo7r38P/3q1fp/0Q950VQ3El68roruhO48i3FMH usQeR43XQP2rcKxFPJbt/ej2VkGfs7AfeaBlaPLE= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-90237: netfilter: nft_ct: move custom expectation support to helper Date: Thu, 17 Sep 2026 17:11:07 +0100 Message-ID: <2026091741-CVE-2026-90237-c5c4@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3600; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=H2/d3jkiXvTUllfsQU4QOTrDBPkbiAQQybxmd5tchfY=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlrBDq3nW9R+WivajNxp8G/bHcjdoWPc1/8XvQpzXTVm rTlu3tSOmJZGASZGGTFFFm+bOM5ur/ikKKXoe1pmDmsTCBDGLg4BWAi62UZ5jvP4Wk9emRzw66f bxKfevWYHlk7u45hftmuxvrZSWL/GbSzeJXtBK5/a5DNBgA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_ct: move custom expectation support to helper Originally, the ct expectation support called nf_ct_helper_ext_add() for confirmed conntracks, which is invalid, triggering a splat. This was fixed by commit 1710eb913bdc ("netfilter: nft_ct: skip expectations for confirmed conntrack") which restricted it to unconfirmed conntracks. However, early insertion of expectations into the expectations list when the conntrack is unconfirmed leads to stale entries pointing to the wrong hlist_head through .pprev due to ct extension reallocation. Commit 7c9664351980 ("netfilter: move nat hlist_head to nf_conn") moved the nat hlist_head to nf_conn for this reason: 1. ... 2. When reallocation of extension area occurs we need to fixup the bysource hash head via hlist_replace_rcu. I'd rather not increase the size of the struct nf_conn for this feature has very limited scope: only one expectation can be created at a time given expect_clash() will make nf_ct_expect_related() reports EBUSY. For this reason, relax nf_ct_expect_related() not to drop packets in case expectation creation fails, therefore, expectation creation becomes best effort. To address this issue, add an internal ct helper and attach it to the conntrack entry to streamline the custom ct expectation support with existing ct helpers. Expose a new nf_conntrack_helper_release() function to release the internal helper that is allocated and attached to the conntrack entry to create the custom expectations. The nft_ct module removal always waits for rcu grace period, then the NULL helper callback is observed after this. This patch also restricts the creation of expectations to different helpers other than this custom helper that is created for this type of expectations. The Linux kernel CVE team has assigned CVE-2026-90237 to this issue. Affected and fixed versions =========================== Issue introduced in 5.3 with commit 857b46027d6f91150797295752581b7155b9d0e1 and fixed in 7.2.6 with commit af3fe52fd108fd38235e4813df62442ed0f1d8ff Issue introduced in 5.3 with commit 857b46027d6f91150797295752581b7155b9d0e1 and fixed in 7.3-rc1 with commit 3679da4ad8be84cddaf40bc307fef1fe13e051ff 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-2026-90237 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: include/net/netfilter/nf_conntrack_helper.h net/netfilter/nf_conntrack_helper.c net/netfilter/nft_ct.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/af3fe52fd108fd38235e4813df62442ed0f1d8ff https://git.kernel.org/stable/c/3679da4ad8be84cddaf40bc307fef1fe13e051ff