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 X-Spam-Level: X-Spam-Status: No, score=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E8D1C43462 for ; Mon, 29 Mar 2021 09:04:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 482F360C3E for ; Mon, 29 Mar 2021 09:04:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237528AbhC2JEU (ORCPT ); Mon, 29 Mar 2021 05:04:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:34816 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234988AbhC2Ijx (ORCPT ); Mon, 29 Mar 2021 04:39:53 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A3E1561477; Mon, 29 Mar 2021 08:39:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1617007181; bh=6wyKLGO9rAeVxiKqS95Q7znjw0mD0+QqYxi/WUlL7lg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TyIrRuxJ8d9mEsOqGhRcdb/h73xKnX+BmV7gQMDCeBAPfeWH7VINPnbB4c5ZLOe8l laSgX7IcARU+dk+SaFg2+svnKTwlpxwo2RKEaHOI6Zpzs1nF6Tc2TNEdiefo+pMLw3 5oiq3CQ4qNsMVQgCqF9Hj8i7KRxJNowTkwsGPr1U= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+a8b4b0c60155e87e9484@syzkaller.appspotmail.com, Sabyrzhan Tasbolatov , Jan Kara , Theodore Tso Subject: [PATCH 5.11 250/254] fs/ext4: fix integer overflow in s_log_groups_per_flex Date: Mon, 29 Mar 2021 09:59:26 +0200 Message-Id: <20210329075641.281708238@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210329075633.135869143@linuxfoundation.org> References: <20210329075633.135869143@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sabyrzhan Tasbolatov commit f91436d55a279f045987e8b8c1385585dca54be9 upstream. syzbot found UBSAN: shift-out-of-bounds in ext4_mb_init [1], when 1 << sbi->s_es->s_log_groups_per_flex is bigger than UINT_MAX, where sbi->s_mb_prefetch is unsigned integer type. 32 is the maximum allowed power of s_log_groups_per_flex. Following if check will also trigger UBSAN shift-out-of-bound: if (1 << sbi->s_es->s_log_groups_per_flex >= UINT_MAX) { So I'm checking it against the raw number, perhaps there is another way to calculate UINT_MAX max power. Also use min_t as to make sure it's uint type. [1] UBSAN: shift-out-of-bounds in fs/ext4/mballoc.c:2713:24 shift exponent 60 is too large for 32-bit type 'int' Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x137/0x1be lib/dump_stack.c:120 ubsan_epilogue lib/ubsan.c:148 [inline] __ubsan_handle_shift_out_of_bounds+0x432/0x4d0 lib/ubsan.c:395 ext4_mb_init_backend fs/ext4/mballoc.c:2713 [inline] ext4_mb_init+0x19bc/0x19f0 fs/ext4/mballoc.c:2898 ext4_fill_super+0xc2ec/0xfbe0 fs/ext4/super.c:4983 Reported-by: syzbot+a8b4b0c60155e87e9484@syzkaller.appspotmail.com Signed-off-by: Sabyrzhan Tasbolatov Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20210224095800.3350002-1-snovitoll@gmail.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/mballoc.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2709,8 +2709,15 @@ static int ext4_mb_init_backend(struct s } if (ext4_has_feature_flex_bg(sb)) { - /* a single flex group is supposed to be read by a single IO */ - sbi->s_mb_prefetch = min(1 << sbi->s_es->s_log_groups_per_flex, + /* a single flex group is supposed to be read by a single IO. + * 2 ^ s_log_groups_per_flex != UINT_MAX as s_mb_prefetch is + * unsigned integer, so the maximum shift is 32. + */ + if (sbi->s_es->s_log_groups_per_flex >= 32) { + ext4_msg(sb, KERN_ERR, "too many log groups per flexible block group"); + goto err_freesgi; + } + sbi->s_mb_prefetch = min_t(uint, 1 << sbi->s_es->s_log_groups_per_flex, BLK_MAX_SEGMENT_SIZE >> (sb->s_blocksize_bits - 9)); sbi->s_mb_prefetch *= 8; /* 8 prefetch IOs in flight at most */ } else {