From mboxrd@z Thu Jan 1 00:00:00 1970 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 82B90C4332F for ; Mon, 14 Nov 2022 12:01:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236586AbiKNMBf (ORCPT ); Mon, 14 Nov 2022 07:01:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35484 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236471AbiKNMBB (ORCPT ); Mon, 14 Nov 2022 07:01:01 -0500 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4077C26548 for ; Mon, 14 Nov 2022 03:59:07 -0800 (PST) Received: from kwepemi500012.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4N9nn31RBSzqSLx; Mon, 14 Nov 2022 19:55:19 +0800 (CST) Received: from [10.67.110.108] (10.67.110.108) 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; Mon, 14 Nov 2022 19:59:04 +0800 Message-ID: <90ca400b-050a-ec3e-b052-2cf1cd34c020@huawei.com> Date: Mon, 14 Nov 2022 19:59:03 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Subject: Re: [PATCH] fs: Fix UBSAN detected shift-out-bounds error for bad superblock To: Jan Kara CC: , , , , , References: <20221114024957.60916-1-liaochang1@huawei.com> <20221114110459.x7yb6rhgwpi6kyjj@quack3> From: "liaochang (A)" In-Reply-To: <20221114110459.x7yb6rhgwpi6kyjj@quack3> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.67.110.108] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) 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 在 2022/11/14 19:04, Jan Kara 写道: > On Mon 14-11-22 10:49:57, Liao Chang wrote: >> UBSAN: shift-out-of-bounds in fs/minix/bitmap.c:103:3 >> shift exponent 8192 is too large for 32-bit type 'unsigned int' >> CPU: 1 PID: 32273 Comm: syz-executor.0 Tainted: G W >> 6.1.0-rc4-dirty #11 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), >> BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014 >> Call Trace: >> >> dump_stack_lvl+0xcd/0x134 >> ubsan_epilogue+0xb/0x50 >> __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x18d >> minix_count_free_blocks.cold+0x16/0x1b >> minix_statfs+0x22a/0x490 >> statfs_by_dentry+0x133/0x210 >> user_statfs+0xa9/0x160 >> __do_sys_statfs+0x7a/0xf0 >> do_syscall_64+0x35/0x80 >> entry_SYSCALL_64_after_hwframe+0x63/0xcd >> >> The superblock stores on disk contains the size of a data zone, which is >> too large to used as the shift when kernel try to calculate the total >> size of zones, so it needs to check the superblock when kernel mounts >> MINIX-FS. >> >> Signed-off-by: Liao Chang > > Thanks for the patch. Just one nit: > >> diff --git a/fs/minix/inode.c b/fs/minix/inode.c >> index da8bdd1712a7..f1d1c2312817 100644 >> --- a/fs/minix/inode.c >> +++ b/fs/minix/inode.c >> @@ -166,6 +166,12 @@ static bool minix_check_superblock(struct super_block *sb) >> sb->s_maxbytes > (7 + 512 + 512*512) * BLOCK_SIZE) >> return false; >> >> + /* the total size of zones must no exceed the limitation of U32_MAX. */ >> + if (sbi->s_log_zone_size && (sbi->s_nzones - sbi->s_firstdatazone) && >> + (__builtin_clzl((__u32)(sbi->s_nzones - sbi->s_firstdatazone)) <= > > Why this strange __builtin_clzl() function? We have a ffs() function in > the kernel for this :) Great suggestion, i should use a compiler neutral API to caclulate leading zero count, what about count_leading_zeros()? Thanks. > > Honza > >> + sbi->s_log_zone_size)) >> + return false; >> + >> return true; >> } >> >> -- >> 2.17.1 >> -- BR, Liao, Chang