From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 6B1302BE057 for ; Wed, 13 May 2026 15:08:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778684935; cv=none; b=VjYZj2IJQnwMrzagkNcKvU2eO50ERBjTwpuKhugvFaEGWdP+SA1pV2+fTvqTmW+cKVoXMxMbmDo2eTfbvAxtgUd1EWbsv88sdJ6XGGcYpFpsFRiAUj+7BrJr36/3YwUq8lRv822lrNgKW3BW9RtcFiy7CaN3JtMmyc3DbzA89Go= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778684935; c=relaxed/simple; bh=GfKPJ0HpIbe3N1nz29Fr91my4AMCOtwZrH7e2U0AWas=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=fLXl6rZKt27hGx8gYgB9Pm+4wwNRba7uWcLdrNUUcBqL6jD8kwoQ6V5dSpCpYMr5vECYCLLBqeEmXwkb11coJwcfbOffR/aw/MXPRpK867N453yF7/wF0FKXOrL/+bP+CCGZ9GrW3djcV6RUVEXACGeDd+DOKJVbWw/AMXM95Ok= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=lI9yoDYi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="lI9yoDYi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8399C19425; Wed, 13 May 2026 15:08:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778684935; bh=GfKPJ0HpIbe3N1nz29Fr91my4AMCOtwZrH7e2U0AWas=; h=From:To:Cc:Subject:Date:Reply-To:From; b=lI9yoDYignKcqAtFP6sbmLDMxKYhSTp79XaLq19QIVp7ADHTPd5W6GQO6Lk1FDwdQ kU40N0qehFszz2N2Un0DNFiZ4XtSjLsej73c9ypQB+XWqEY/fZesOf1Fs9qw25WDvc f2KSLppWbqRt6qzRAOPQvSZoI0rrO7UrYEnITFGU= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-43486: arm64: contpte: fix set_access_flags() no-op check for SMMU/ATS faults Date: Wed, 13 May 2026 17:08:54 +0200 Message-ID: <2026051349-CVE-2026-43486-b3b9@gregkh> X-Mailer: git-send-email 2.54.0 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=3713; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=kDHB5/kFnQ95n9IR7jExeHT/wI3YtyVFtunSJ5JmT1Y=; b=owGbwMvMwCRo6H6F97bub03G02pJDFksUxjnt/xI/vc50nbGkd5LpeetNX76hlny/JqqI93Cs TYk8NqhjlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZiI9D+G+Tmn+uetSO2X/LCZ 432hqcRW6ayeSQzz/aMfL7TN01Lf35+UvvL8L6FpXR/XAAA= 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: arm64: contpte: fix set_access_flags() no-op check for SMMU/ATS faults contpte_ptep_set_access_flags() compared the gathered ptep_get() value against the requested entry to detect no-ops. ptep_get() ORs AF/dirty from all sub-PTEs in the CONT block, so a dirty sibling can make the target appear already-dirty. When the gathered value matches entry, the function returns 0 even though the target sub-PTE still has PTE_RDONLY set in hardware. For a CPU with FEAT_HAFDBS this gathered view is fine, since hardware may set AF/dirty on any sub-PTE and CPU TLB behavior is effectively gathered across the CONT range. But page-table walkers that evaluate each descriptor individually (e.g. a CPU without DBM support, or an SMMU without HTTU, or with HA/HD disabled in CD.TCR) can keep faulting on the unchanged target sub-PTE, causing an infinite fault loop. Gathering can therefore cause false no-ops when only a sibling has been updated: - write faults: target still has PTE_RDONLY (needs PTE_RDONLY cleared) - read faults: target still lacks PTE_AF Fix by checking each sub-PTE against the requested AF/dirty/write state (the same bits consumed by __ptep_set_access_flags()), using raw per-PTE values rather than the gathered ptep_get() view, before returning no-op. Keep using the raw target PTE for the write-bit unfold decision. Per Arm ARM (DDI 0487) D8.7.1 ("The Contiguous bit"), any sub-PTE in a CONT range may become the effective cached translation and software must maintain consistent attributes across the range. The Linux kernel CVE team has assigned CVE-2026-43486 to this issue. Affected and fixed versions =========================== Issue introduced in 6.9 with commit 4602e5757bcceb231c3a13c36c373ad4a750eddb and fixed in 6.12.78 with commit 05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0 Issue introduced in 6.9 with commit 4602e5757bcceb231c3a13c36c373ad4a750eddb and fixed in 6.18.19 with commit 6f92a7a8b48a523f910ef25dd83808710724f59b Issue introduced in 6.9 with commit 4602e5757bcceb231c3a13c36c373ad4a750eddb and fixed in 6.19.9 with commit 09d620555e59768776090073a2c59d2bc8506eb3 Issue introduced in 6.9 with commit 4602e5757bcceb231c3a13c36c373ad4a750eddb and fixed in 7.0 with commit 97c5550b763171dbef61e6239cab372b9f9cd4a2 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-2026-43486 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: arch/arm64/mm/contpte.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/05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0 https://git.kernel.org/stable/c/6f92a7a8b48a523f910ef25dd83808710724f59b https://git.kernel.org/stable/c/09d620555e59768776090073a2c59d2bc8506eb3 https://git.kernel.org/stable/c/97c5550b763171dbef61e6239cab372b9f9cd4a2