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 B8994376A03 for ; Sat, 15 Aug 2026 06:27:02 +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=1786775223; cv=none; b=XQon7Q68pUcrI7atkXELot6STmNGujYatCCASl9ial2uLcElFRppW/NneR8WnD4GnkKXZct1bu7GlfbUVKWuWzbz8C5cN/wGzt1KkOQYeqGM7ChE1P8GgzVjOBPjIt1bLonSWPt7Dpk0eAy/YZXweWh4EEYop/sCP+Ei2qeDP1E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786775223; c=relaxed/simple; bh=3VaBPKfEJh+4UxfLe0PyUlkeH41xZRfRJgFODmX/LZk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=d5ro3lF4PNxk3iEVQE8QEwg4pQodmPLZGWLLIjdOccRjO0AN2ZMvD45oWG43JM4zcn7jEm57ulbVX2V9Z/4kPYQauyQpsmTa1Im51UbdD9ZLAeY6sL0nyFTkynAuj0ku9KwHbI3wzRfbxREsTZoWFsA41pKoqaqjZkYSRFgMPbc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Dg2fkHHh; 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="Dg2fkHHh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 142F01F00A3A; Sat, 15 Aug 2026 06:27:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786775222; bh=fWAa752owdopeKRLuKl/jS0HuwX5H1H9CWvqFr9nEXQ=; h=From:To:Cc:Subject:Date:Reply-To; b=Dg2fkHHhPHQdQWcL4FEVI4YhFQi3de0wA60d1zQLSfpIMjJGZVAaKS5+8bPX8JkBd j1pmYyEV+DTEVmmgo7iXj8jtpZ2EBxK6xazuZOAnLOE9YwljbwCdAiRHEVcoqmXWYV TOTe/3ck+3ZCzkj5B6vheVx1QimyO9xXpq66+aDo= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-72412: s390/mm: Fix handling of _PAGE_UNUSED pte bit Date: Sat, 15 Aug 2026 15:08:11 +0900 Message-ID: <2026081523-CVE-2026-72412-ed70@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=2789; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=wR3shApFHn3l7Qv1LsqtxIXThxH9bG2yUaQkUBn+h9g=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkNDB/iD4Um/X3B5dKa03ZyS9Hvb0VOh3/M2/HhkKnz9 WNftB5e7IhlYRBkYpAVU2T5so3n6P6KQ4pehranYeawMoEMYeDiFICJaGYzzFMO2MKsf/r7He7f K9o5PG6+XXHywxyGuXIKW05zuj6WX1ZRcHfW8rjKpt/6awA= 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: s390/mm: Fix handling of _PAGE_UNUSED pte bit The _PAGE_UNUSED softbit should not really be lying around. Its sole purpose is to signal to try_to_unmap_one() and try_to_migrate_one() that the page can be discarded instead of being moved / swapped. KVM has no way to know why a page is being unmapped, so it sets the bit on userspace ptes corresponding to unused guest pages every time they get unmapped. KVM has no reasonable way to clear the bit once the page is in use again. While set_ptes() checks and clears the bit, other paths that set new ptes did not. This led to used pages being thrown out as if they were unused, causing guest corruption. Fix the issue by clearing the _PAGE_UNUSED bit for present ptes in set_pte(), i.e. whenever a present pte is getting set. The check in set_ptes() is then redundant and can be removed. Also fix gmap_helper_try_set_pte_unused() to only set the bit if the pte is present; the _PAGE_UNUSED bit is only defined for present ptes and thus should not be set for non-present ptes. The Linux kernel CVE team has assigned CVE-2026-72412 to this issue. Affected and fixed versions =========================== Issue introduced in 7.0 with commit c98175b7917fa81cd499b1527c4a57fd7d36711e and fixed in 7.1.5 with commit fda07c8e4b54b9105f1ca73f0adea7b244d405f4 Issue introduced in 7.0 with commit c98175b7917fa81cd499b1527c4a57fd7d36711e and fixed in 7.2-rc1 with commit d4bb00704a66024502261fa7a523c07420249fea 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-2026-72412 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/s390/include/asm/pgtable.h arch/s390/mm/gmap_helpers.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/fda07c8e4b54b9105f1ca73f0adea7b244d405f4 https://git.kernel.org/stable/c/d4bb00704a66024502261fa7a523c07420249fea