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 C21D0563287 for ; Fri, 11 Sep 2026 20:06:09 +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=1789157172; cv=none; b=Mvcaq/sxZjBGIyEX+okc3FpfBJmSVT3D6bYawgOe+3v7YrigsVO3umRokcbThHwOF5qaFpIW7M7RUBbtD3ul+ZNzDZyqaUo2+2+DZHxwdYCLQz76DqBgz7dEObdE6Wws9ka30CvnRn/BiAKTm3VhXaj8DapK20gTaqBMx5s1FZ4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789157172; c=relaxed/simple; bh=E5OqqpNHwN/O6UUNKqfAH0V6DF/fkTm9dZEGc0mNMVA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Dhk59oT8GwHRddymzj4I0aXVpzu9/u8Nk0sdPmXR82UDvw+FrirJkl2TnTZCLF7pXXNwqMnMyy/TqbuvsU0KcoSHNaWtpiATZpv5V5aBTCGvJTHMs+OofbTc3+bm8PAKBMrFlOMnCl9b1hnQ95Abxszl+WlEbVX78XE1hdLYzyQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=a6Vo6ZFq; 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="a6Vo6ZFq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4CCB41F00893; Fri, 11 Sep 2026 20:06:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789157166; bh=JfO5NpN+Ku5EI9IhN3ng4dDs8tNSVhIBUa5AwZt/dMc=; h=From:To:Cc:Subject:Date:Reply-To; b=a6Vo6ZFqNj25ssqWtulJHSEbzVfCnKj2elZFKoxweoDEJBQT8D3zbY8NtGoKDXxyq Ba27RNQBMWZ8afc6eewrl5gAYoHqRCM1wlIDV2btS0MxtJ9BKFhoi3Osm8L7yn2yH7 9IMqMU9TjJmsGnDl8rg0WFTH98Ii0amPhm4kq82Y= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89758: mm/mempolicy: skip non-present PMDs when queueing folios Date: Fri, 11 Sep 2026 21:47:27 +0200 Message-ID: <2026091108-CVE-2026-89758-5c07@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=3241; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=NgErMfOPvAycm2NeZ2dPWucImrnA7lysUkse2V+2Ba8=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIifsc/zHIrf10JK/rX+DYlqnf5ZqSpu91XU7i/fMx ENPDM/t7IhlYRBkYpAVU2T5so3n6P6KQ4pehranYeawMoEMYeDiFICJvF/PMIe7y18mwVi00C77 25uFaxbv05LR+8UwV4Q7eKNPd/+9Sy9myQcck7H6Up4fAAA= 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/mempolicy: skip non-present PMDs when queueing folios Patch series "mm: handle device-private PMDs in walk callbacks", v3. Since commit 368076f52ebe ("mm/huge_memory: add device-private THP support to PMD operations") a PMD may hold a device-private swap entry whenever an HMM-based GPU driver migrates an anonymous THP folio to device memory via migrate_vma_pages(). pmd_trans_huge_lock() succeeds for such PMDs (pmd_is_huge() returns true for any non-present, non-none huge PMD), so several MM walk callbacks that used to assume present THP or migration entry are now reachable with a device-private PMD. The results range from a VM_BUG_ON() firing on debug kernels, to an oops on a bogus vmemmap dereference, to silently isolating an unrelated live folio from LRU in the aliasing case. This patch (of 3): queue_folios_pmd() is called under pmd_trans_huge_lock(), whose pmd_is_huge() check returns true for any non-present, non-none PMD softleaf. Passing such a PMD to pmd_folio() treats the softleaf encoding as a hardware PFN and can return a bogus folio pointer. Mirror queue_folios_pte_range(): handle non-present entries before looking up a folio. Keep migration entries counted as failures, but skip other non-present PMDs such as device-private entries. Potential trigger: an HMM-based GPU driver migrates an anonymous THP folio to device memory via migrate_vma_pages(), leaving a device-private PMD. Userspace then calls mbind(), migrate_pages() or set_mempolicy_home_node() on that range. The Linux kernel CVE team has assigned CVE-2026-89758 to this issue. Affected and fixed versions =========================== Issue introduced in 6.19 with commit 368076f52ebeecd33e10a9f80905d7508b6b6149 and fixed in 7.2.4 with commit 3d927093b2add7ced588a926c3dc5d7a83f18596 Issue introduced in 6.19 with commit 368076f52ebeecd33e10a9f80905d7508b6b6149 and fixed in 7.3-rc1 with commit 2858b4027f491e6fdb8ee2d8923798b619bf2791 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-2026-89758 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/mempolicy.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/3d927093b2add7ced588a926c3dc5d7a83f18596 https://git.kernel.org/stable/c/2858b4027f491e6fdb8ee2d8923798b619bf2791