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 5A7093EFD22 for ; Fri, 8 May 2026 14:24:55 +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=1778250295; cv=none; b=SmMKo35EZkBSiv9+f8OhZwlvAnn27MxbraE7X8Fe4JHH0AxNyUTJQAgxAl9TEMGUFHSAatq0y5rvDeaCRWFaf2vsq22DmZGupEX+XpfTOn/OGSkhK8c7Fw35aN4Tf4ViAnPskjB45DXq6mJHfpnN5YSwosuDjJ8PhNMR0xrYjv0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778250295; c=relaxed/simple; bh=AZAbHdcaG/37gS4TKjXedhaqk8QD98tPCudyojV4gNo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ndJ7Kw3UtcxBYcNh5cMZYp/UQHdx5vJR2x4uj8ZucThn/h/kpjfp6iLw5Ruofp5FjUJZEcb5XdBd+CyLxJtEfDL4IszsaVfQPYbp8ErzvfiPr0EX9vDoQCraWNOOY7VxXbvrr5KKM84fY1fuPUClCfQLE90cvAqarUm93NbcfD0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xQThxzLu; 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="xQThxzLu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E94D4C2BCB0; Fri, 8 May 2026 14:24:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778250295; bh=AZAbHdcaG/37gS4TKjXedhaqk8QD98tPCudyojV4gNo=; h=From:To:Cc:Subject:Date:Reply-To:From; b=xQThxzLu6OolUPkCSvARGV0uz2Lbc602sOL6uNa7+Z00drvFNMKJMVf4oK6PIf6L9 9IQYWWthQ1pu1yJ5HrHM7toQMmoWUxZKtIDHdeTvYrre06cYr3iB7ihKnLcBjuwKIj PSScArqiM/lpQGOeXSTfFsZa5ccH3joVlq3GZEw4= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-43389: mm: memfd_luo: always dirty all folios Date: Fri, 8 May 2026 16:21:58 +0200 Message-ID: <2026050836-CVE-2026-43389-059e@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=2902; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=3NqZJPX6sXJNpjm55HZmjiJeAKoMIUfi98kOcRKxVEY=; b=owGbwMvMwCRo6H6F97bub03G02pJDJl/PxZITFZtuLlh8V2ZLY5/X3zQ2Hda9a2QU7rVhtzZw WlBxhGXO2JZGASZGGTFFFm+bOM5ur/ikKKXoe1pmDmsTCBDGLg4BWAi4iYM891urHqgtPPKvbPK FxdovWu3UruWycowP7KX86zj/SdZVy/9Cm6Zsbaj/+DLZQA= 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: mm: memfd_luo: always dirty all folios A dirty folio is one which has been written to. A clean folio is its opposite. Since a clean folio has no user data, it can be freed under memory pressure. memfd preservation with LUO saves the flag at preserve(). This is problematic. The folio might get dirtied later. Saving it at freeze() also doesn't work, since the dirty bit from PTE is normally synced at unmap and there might still be mappings of the file at freeze(). To see why this is a problem, say a folio is clean at preserve, but gets dirtied later. The serialized state of the folio will mark it as clean. After retrieve, the next kernel will see the folio as clean and might try to reclaim it under memory pressure. This will result in losing user data. Mark all folios of the file as dirty, and always set the MEMFD_LUO_FOLIO_DIRTY flag. This comes with the side effect of making all clean folios un-reclaimable. This is a cost that has to be paid for participants of live update. It is not expected to be a common use case to preserve a lot of clean folios anyway. Since the value of pfolio->flags is a constant now, drop the flags variable and set it directly. The Linux kernel CVE team has assigned CVE-2026-43389 to this issue. Affected and fixed versions =========================== Issue introduced in 6.19 with commit b3749f174d686627f702234e64bad976dc432dbc and fixed in 6.19.9 with commit e901c871d4b592f0042e30f3a0f031eae79744ec Issue introduced in 6.19 with commit b3749f174d686627f702234e64bad976dc432dbc and fixed in 7.0 with commit 7e04bf1f33151a30e06a65b74b5f2c19fc2be128 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-2026-43389 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: mm/memfd_luo.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/e901c871d4b592f0042e30f3a0f031eae79744ec https://git.kernel.org/stable/c/7e04bf1f33151a30e06a65b74b5f2c19fc2be128