From nobody Mon Feb 9 05:41:52 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 72964C77B75 for ; Fri, 12 May 2023 10:33:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240508AbjELKdk (ORCPT ); Fri, 12 May 2023 06:33:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240641AbjELKcD (ORCPT ); Fri, 12 May 2023 06:32:03 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D8FC3D06C for ; Fri, 12 May 2023 03:31:53 -0700 (PDT) Received: from kwepemi500009.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4QHlMF4bbFzqSJm; Fri, 12 May 2023 18:27:37 +0800 (CST) Received: from huawei.com (10.67.175.85) by kwepemi500009.china.huawei.com (7.221.188.199) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Fri, 12 May 2023 18:31:51 +0800 From: Xia Fukun To: , CC: , Subject: [PATCH v4] kobject: Fix global-out-of-bounds in kobject_action_type() Date: Fri, 12 May 2023 18:30:29 +0800 Message-ID: <20230512103029.183852-1-xiafukun@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.67.175.85] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemi500009.china.huawei.com (7.221.188.199) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The following c language code can trigger KASAN's global variable out-of-bounds access error in kobject_action_type(): int main() { int fd; char *filename =3D "/sys/block/ram12/uevent"; char str[86] =3D "offline"; int len =3D 86; fd =3D open(filename, O_WRONLY); if (fd =3D=3D -1) { printf("open"); exit(1); } if (write(fd, str, len) =3D=3D -1) { printf("write"); exit(1); } close(fd); return 0; } Function kobject_action_type() receives the input parameters buf and count, where count is the length of the string buf. In the use case we provided, count is 86, the count_first is 85. Buf points to a string with a length of 86, and its first seven characters are "offline". In line 87 of the code, kobject_actions[action] is the string "offline" with the length of 7,an out-of-boundary access will appear: kobject_actions[action][85]. Use sysfs_match_string() to replace the fragile and convoluted loop. This function is well-tested for parsing sysfs inputs. Moreover, this modification will not cause any functional changes. Fixes: f36776fafbaa ("kobject: support passing in variables for synthetic u= events") Signed-off-by: Xia Fukun --- v3 -> v4: - refactor the function to be more obviously correct and readable v2 -> v3: - only declare that it is the latest version of the patch, no change v1 -> v2: - modify the matching logic lib/kobject_uevent.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c index 7c44b7ae4c5c..59f835f5f870 100644 --- a/lib/kobject_uevent.c +++ b/lib/kobject_uevent.c @@ -66,7 +66,7 @@ static int kobject_action_type(const char *buf, size_t co= unt, enum kobject_action action; size_t count_first; const char *args_start; - int ret =3D -EINVAL; + int i, ret =3D -EINVAL; =20 if (count && (buf[count-1] =3D=3D '\n' || buf[count-1] =3D=3D '\0')) count--; @@ -81,17 +81,20 @@ static int kobject_action_type(const char *buf, size_t = count, } else count_first =3D count; =20 - for (action =3D 0; action < ARRAY_SIZE(kobject_actions); action++) { - if (strncmp(kobject_actions[action], buf, count_first) !=3D 0) - continue; - if (kobject_actions[action][count_first] !=3D '\0') - continue; - if (args) - *args =3D args_start; - *type =3D action; - ret =3D 0; - break; - } + /* Use sysfs_match_string() to replace the fragile and convoluted loop */ + i =3D sysfs_match_string(kobject_actions, buf); + + if (i < 0) + return ret; + + action =3D kobject_action(i); + + if (args) + *args =3D args_start; + + *type =3D action; + ret =3D 0; + out: return ret; } --=20 2.17.1