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 888A1C433FE for ; Mon, 14 Nov 2022 12:07:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236955AbiKNMHx (ORCPT ); Mon, 14 Nov 2022 07:07:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40248 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236748AbiKNMHi (ORCPT ); Mon, 14 Nov 2022 07:07:38 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A016CE34 for ; Mon, 14 Nov 2022 04:07:34 -0800 (PST) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 0175C2273D; Mon, 14 Nov 2022 12:07:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1668427653; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=jruMgBY5bV0IXTFQWV3qYvuLQLTE5ZFImlMF2xpEA5Y=; b=sEfZ7E1DbAUbXgkCZIRMQBKYjhXWPZLUTuP/QJOjUKZ38ukEIIqjuSLbFf+nP6Y/uXC3YO g3tVfmjTroj0w1pKMIu7IF8FibtgDEr7Rvhzu0SiTWLwINV/PSdqjydbOq8WMaeh8R247G ouDPiCuQFhNJiz7rutSmXtsi3z6Md4s= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1668427653; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=jruMgBY5bV0IXTFQWV3qYvuLQLTE5ZFImlMF2xpEA5Y=; b=Zwz2Ev7xCTDiFs9XtgZx8PRSSNNW90giG+TDpHPMY98qrn+h7ZxAWYXGyDto3tuhPD9fiJ +oVfU9bvluhFWJCg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id E3FAC13A92; Mon, 14 Nov 2022 12:07:32 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id xF6kN4QvcmMaEQAAMHmgww (envelope-from ); Mon, 14 Nov 2022 12:07:32 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 7089EA0709; Mon, 14 Nov 2022 13:07:32 +0100 (CET) Date: Mon, 14 Nov 2022 13:07:32 +0100 From: Jan Kara To: "liaochang (A)" Cc: Jan Kara , willy@infradead.org, damien.lemoal@opensource.wdc.com, akpm@linux-foundation.org, qhjin.dev@gmail.com, songmuchun@bytedance.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] fs: Fix UBSAN detected shift-out-bounds error for bad superblock Message-ID: <20221114120732.vephphzzpdkv2zam@quack3> References: <20221114024957.60916-1-liaochang1@huawei.com> <20221114110459.x7yb6rhgwpi6kyjj@quack3> <90ca400b-050a-ec3e-b052-2cf1cd34c020@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <90ca400b-050a-ec3e-b052-2cf1cd34c020@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 14-11-22 19:59:03, liaochang (A) wrote: > > > 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()? Yeah, that would work as well. Honza -- Jan Kara SUSE Labs, CR