From nobody Mon Feb 9 08:20:06 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3EFC2C77B7A for ; Wed, 7 Jun 2023 13:26:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240248AbjFGN0W (ORCPT ); Wed, 7 Jun 2023 09:26:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235032AbjFGN0U (ORCPT ); Wed, 7 Jun 2023 09:26:20 -0400 Received: from frasgout11.his.huawei.com (unknown [14.137.139.23]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8DB381AC; Wed, 7 Jun 2023 06:26:19 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.18.147.228]) by frasgout11.his.huawei.com (SkyGuard) with ESMTP id 4QbnsK34lVz9xGgS; Wed, 7 Jun 2023 21:15:49 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwCH9O9thYBk6e8aAw--.4240S2; Wed, 07 Jun 2023 14:26:09 +0100 (CET) From: Roberto Sassu To: akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, Roberto Sassu , stable@vger.kernel.org Subject: [PATCH] memfd: Check for non-NULL file_seals in memfd_create() syscall Date: Wed, 7 Jun 2023 15:24:27 +0200 Message-Id: <20230607132427.2867435-1-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: LxC2BwCH9O9thYBk6e8aAw--.4240S2 X-Coremail-Antispam: 1UD129KBjvdXoWrZF15tFW7JFW7uF4UWFykXwb_yoWkAwbEg3 y0qryrJr1DWw47CF4xAr13Zry8KFWDJrnxZF95tF4xAa98Ga1kWrZ3ur1fX348Gw4I9r1r tFZrZF17Ar97GjkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUb7xYFVCjjxCrM7AC8VAFwI0_Jr0_Gr1l1xkIjI8I6I8E6xAIw20E Y4v20xvaj40_Wr0E3s1l1IIY67AEw4v_Jr0_Jr4l8cAvFVAK0II2c7xJM28CjxkF64kEwV A0rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVWUJVWUCwA2z4x0Y4vE2Ix0cI8IcVCY1x02 67AKxVW8JVWxJwA2z4x0Y4vEx4A2jsIE14v26r4j6F4UM28EF7xvwVC2z280aVCY1x0267 AKxVW8Jr0_Cr1UM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40E x7xfMcIj6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x 0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lc7CjxVAaw2AFwI0_GFv_Wryl42xK82IYc2Ij 64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x 8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI7VAKI48JMIIF0xvE 2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42 xK8VAvwI8IcIk0rVW3JVWrJr1lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY 1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x07jx3ktUUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAQABBF1jj45W0QAAs8 X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Roberto Sassu Ensure that file_seals is non-NULL before using it in the memfd_create() syscall. One situation in which memfd_file_seals_ptr() could return a NULL pointer is when CONFIG_SHMEM=3Dn. Cc: stable@vger.kernel.org # 4.16.x Fixes: 47b9012ecdc7 ("shmem: add sealing support to hugetlb-backed memfd") Signed-off-by: Roberto Sassu --- mm/memfd.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/memfd.c b/mm/memfd.c index 69b90c31d38..e763e76f110 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -371,12 +371,15 @@ SYSCALL_DEFINE2(memfd_create, =20 inode->i_mode &=3D ~0111; file_seals =3D memfd_file_seals_ptr(file); - *file_seals &=3D ~F_SEAL_SEAL; - *file_seals |=3D F_SEAL_EXEC; + if (file_seals) { + *file_seals &=3D ~F_SEAL_SEAL; + *file_seals |=3D F_SEAL_EXEC; + } } else if (flags & MFD_ALLOW_SEALING) { /* MFD_EXEC and MFD_ALLOW_SEALING are set */ file_seals =3D memfd_file_seals_ptr(file); - *file_seals &=3D ~F_SEAL_SEAL; + if (file_seals) + *file_seals &=3D ~F_SEAL_SEAL; } =20 fd_install(fd, file); --=20 2.25.1