From nobody Wed Apr 8 20:08:36 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 BBF3AFA3740 for ; Sat, 29 Oct 2022 07:17:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229716AbiJ2HRu (ORCPT ); Sat, 29 Oct 2022 03:17:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60590 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229602AbiJ2HRs (ORCPT ); Sat, 29 Oct 2022 03:17:48 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 208F3180AF2; Sat, 29 Oct 2022 00:17:48 -0700 (PDT) Received: from kwepemi500012.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4MzrGT3w59z15MFW; Sat, 29 Oct 2022 15:12:49 +0800 (CST) Received: from cgs.huawei.com (10.244.148.83) by kwepemi500012.china.huawei.com (7.221.188.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Sat, 29 Oct 2022 15:17:45 +0800 From: Gaosheng Cui To: , , CC: , Subject: [PATCH] fs: fix undefined behavior in bit shift for SB_NOUSER Date: Sat, 29 Oct 2022 15:17:45 +0800 Message-ID: <20221029071745.2836665-1-cuigaosheng1@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.244.148.83] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemi500012.china.huawei.com (7.221.188.12) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Shifting signed 32-bit value by 31 bits is undefined, so changing most significant bit to unsigned. The UBSAN warning calltrace like below: UBSAN: shift-out-of-bounds in fs/namespace.c:2330:33 left shift of 1 by 31 places cannot be represented in type 'int' Call Trace: dump_stack_lvl+0x7d/0xa5 dump_stack+0x15/0x1b ubsan_epilogue+0xe/0x4e __ubsan_handle_shift_out_of_bounds+0x1e7/0x20c graft_tree+0x36/0xf0 do_add_mount+0x98/0x100 path_mount+0xbd6/0xd50 init_mount+0x6a/0xa3 devtmpfs_setup+0x47/0x7e devtmpfsd+0x1a/0x50 kthread+0x126/0x160 ret_from_fork+0x1f/0x30 Fixes: e462ec50cb5f ("VFS: Differentiate mount flags (MS_*) from internal s= uperblock flags") Signed-off-by: Gaosheng Cui --- include/linux/fs.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 85015e21b755..a68d5310be7b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1396,7 +1396,7 @@ extern int send_sigurg(struct fown_struct *fown); #define SB_NOSEC (1<<28) #define SB_BORN (1<<29) #define SB_ACTIVE (1<<30) -#define SB_NOUSER (1<<31) +#define SB_NOUSER (1U<<31) =20 /* These flags relate to encoding and casefolding */ #define SB_ENC_STRICT_MODE_FL (1 << 0) --=20 2.25.1