From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-99.freemail.mail.aliyun.com (out30-99.freemail.mail.aliyun.com [115.124.30.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DEFA713CABC for ; Mon, 14 Oct 2024 06:33:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.99 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728887640; cv=none; b=HnAx5W7UYmVqUFRI2A02JD2EnGaTYZosXXVdRen08v9Duxm0r5hvu/PnZNVBHdfVEQFWz30Tn/T+oAOJSazbrgdgUU/w6i6whGKu6eRyRO4mua83w2fALjuRYSssATOsywvMW5UI8J+AsoZzDmSGHp5zjTYIHduqTnRf8Y3uUvk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728887640; c=relaxed/simple; bh=vI6zfZOAnEVuWkZk+6GqCLQDFURf4rfFVzjuwaY+aRE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=F/xSz9Y8VK01X8qB/6GOUcYUlZ+f3b5Qo8UD1YWMyDrrd9ypJ5pc6unvO/eOc209F7CyRy5yOHty31ol9HMbvwJWAehf+wXrjkWuzRz1HH3p8Wci1d2CrxC46DHce2sNo3cxXo6hqG7+iGxo+KxFbTczuZtWPg/g1Zke46vfEeA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=gU4/39Uk; arc=none smtp.client-ip=115.124.30.99 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="gU4/39Uk" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1728887636; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=9iTqTFZay+eh5uh2AMI2uElpAwer6VJtK6rahZrN4AE=; b=gU4/39UkF6tCrCMDNyOtAv+55p8G6pbNycKljLeYVeHBEU7PAZp+Xb6KFs23Wl0Lbyjpa7ywaHKT2aHtBwHW4Q4TJTte/CajMQNNnbgFndNGEKfDqMqdyFHWI6r9kvl+7eX22lIT4Ak6Kv3ecHg9YSbycw3BvuWi0RvgOlpMRZY= Received: from 30.221.132.11(mailfrom:joseph.qi@linux.alibaba.com fp:SMTPD_---0WH10Xau_1728887635 cluster:ay36) by smtp.aliyun-inc.com; Mon, 14 Oct 2024 14:33:55 +0800 Message-ID: <431f1d14-ba07-4903-ab02-b4628e0f1973@linux.alibaba.com> Date: Mon, 14 Oct 2024 14:33:54 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V2] ocfs2: BUG is meaningless when the flags is 0 To: Edward Adam Davis Cc: jlbec@evilplan.org, linux-kernel@vger.kernel.org, mark@fasheh.com, ocfs2-devel@lists.linux.dev, syzbot+797d4829dafe3f11dce7@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com References: Content-Language: en-US From: Joseph Qi In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/14/24 7:31 AM, Edward Adam Davis wrote: > Syzbot reported a BUG in ocfs2_read_virt_blocks. > ------------[ cut here ]------------ > kernel BUG at fs/ocfs2/extent_map.c:971! > Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI > CPU: 1 UID: 0 PID: 5221 Comm: syz-executor117 Not tainted 6.12.0-rc2-syzkaller-00006-g87d6aab2389e #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 > RIP: 0010:ocfs2_read_virt_blocks+0xaa3/0xb20 fs/ocfs2/extent_map.c:971 > Code: 8b 54 24 30 8b 4c 24 1c 4c 8b 44 24 38 45 89 e1 ff 74 24 48 e8 7e 0a 0c 00 48 83 c4 08 eb 25 e8 43 d2 34 08 e8 ee d1 0c fe 90 <0f> 0b e8 e6 d1 0c fe 4c 89 e8 45 89 e5 49 89 c4 e9 01 f7 ff ff e8 > RSP: 0018:ffffc90002e2e820 EFLAGS: 00010293 > RAX: ffffffff83881432 RBX: 0000000000000000 RCX: ffff88802d3e9e00 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: ffffc90002e2e9f0 R08: ffffffff83880eae R09: 1ffffffff203781d > R10: dffffc0000000000 R11: fffffbfff203781e R12: ffff8880764d8878 > R13: 0000000000000000 R14: 0000000000000000 R15: 1ffff920005c5d18 > FS: 000055557cd55380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00005628fd41e058 CR3: 000000002d2e6000 CR4: 00000000003526f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > > ocfs2_read_dir_block+0x106/0x5c0 fs/ocfs2/dir.c:508 > ocfs2_find_dir_space_el fs/ocfs2/dir.c:3427 [inline] // status = ocfs2_read_dir_block(dir, 0, &bh, 0); Keep the original stacks is enough. > ocfs2_prepare_dir_for_insert+0x3f2/0x5c60 fs/ocfs2/dir.c:4274 > ocfs2_mknod+0xcaf/0x2b40 fs/ocfs2/namei.c:292 > ocfs2_create+0x1ab/0x480 fs/ocfs2/namei.c:672 > lookup_open fs/namei.c:3595 [inline] > open_last_lookups fs/namei.c:3694 [inline] > path_openat+0x1c03/0x3590 fs/namei.c:3930 > do_filp_open+0x235/0x490 fs/namei.c:3960 > do_sys_openat2+0x13e/0x1d0 fs/open.c:1415 > do_sys_open fs/open.c:1430 [inline] > __do_sys_openat fs/open.c:1446 [inline] > __se_sys_openat fs/open.c:1441 [inline] > __x64_sys_openat+0x247/0x2a0 fs/open.c:1441 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > It is because the parameter v_block passed to ocfs2_read_virt_blocks() is 0, > nr is 1, and inode->i_size is 0, and flags are also 0. > In this path, v_block, flags, and nr are fixed values that are hard coded, > so if i_size is 0, the bug will be triggered. > Therefore, it is more meaningful to check if the flags contain the READHEAD > bit when their value is non-zero. > > Reported-and-tested-by: syzbot+797d4829dafe3f11dce7@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=797d4829dafe3f11dce7 > Signed-off-by: Edward Adam Davis > --- > V1 -> V2: keep rc to 0 when falgs contains READHEAD > > fs/ocfs2/extent_map.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c > index f7672472fa82..0043c2428ef2 100644 > --- a/fs/ocfs2/extent_map.c > +++ b/fs/ocfs2/extent_map.c > @@ -968,7 +968,8 @@ int ocfs2_read_virt_blocks(struct inode *inode, u64 v_block, int nr, > > if (((v_block + nr - 1) << inode->i_sb->s_blocksize_bits) >= > i_size_read(inode)) { > - BUG_ON(!(flags & OCFS2_BH_READAHEAD)); > + BUG_ON(flags && !(flags & OCFS2_BH_READAHEAD)); I don't think this is a right fix. As you described in commit log, I think the root cause is the inode size is 0, which mean no blocks actually. So it seems we have to add a sanity check for this case. Thanks, Joseph > + rc = flags ? 0 : -EIO; > goto out; > } >