From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) (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 D116A1CD18; Sat, 17 Feb 2024 07:41:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.191 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708155710; cv=none; b=pucy7PyxjUChEdbW577FlY212d+8U3v8p5C9GD99V26ST/mUgPuTecAzTBf0l3NOnzCQrGbzge8D85E0OfdXCYqilo7eevk1i6FFjwuWEKN/FcHluZ558e1RHtnnE3Fs5cuCrqH1ewWoHNfCzEeGoYVR/5r3VZo/f2RBmgQjhKE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708155710; c=relaxed/simple; bh=nJTE1jqmCGpZ2lQwYibqNBYEZ8IaoRmC3Ai6HV4eQ1s=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=GwFJ01WysokZZyHD5ircHdaJEaVRNAFt2MTHIeTofv2NrqqqK/wSaOiIVEsOMnk9TPlw/0szXcgnkAfZHQa1tmffTNMKa+6Yb7fAXnTnbbmbnrWMo8dby4Hzqdw2Bi5kiBXsJGCMHQ7jnAmsmvkyDvbBx3d38CIj3IQ3nih2QB4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.191 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.163]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4TcLGd2kfGz1FKZN; Sat, 17 Feb 2024 15:36:57 +0800 (CST) Received: from dggpeml500021.china.huawei.com (unknown [7.185.36.21]) by mail.maildlp.com (Postfix) with ESMTPS id A29A718001B; Sat, 17 Feb 2024 15:41:44 +0800 (CST) Received: from [10.174.177.174] (10.174.177.174) by dggpeml500021.china.huawei.com (7.185.36.21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Sat, 17 Feb 2024 15:41:43 +0800 Message-ID: <83c16b1a-832d-2ffd-6100-1f2b80ca2f35@huawei.com> Date: Sat, 17 Feb 2024 15:41:43 +0800 Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.1.2 Subject: Re: [PATCH 4/7] ext4: add positive int attr pointer to avoid sysfs variables overflow Content-Language: en-US To: Jan Kara CC: , , , , , , , , , , Baokun Li References: <20240126085716.1363019-1-libaokun1@huawei.com> <20240126085716.1363019-5-libaokun1@huawei.com> <20240213165810.3k4lnxaqzdwrdj35@quack3> From: Baokun Li In-Reply-To: <20240213165810.3k4lnxaqzdwrdj35@quack3> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpeml500021.china.huawei.com (7.185.36.21) On 2024/2/14 0:58, Jan Kara wrote: > On Fri 26-01-24 16:57:13, Baokun Li wrote: >> We can easily trigger a BUG_ON by using the following commands: >> >> mount /dev/$disk /tmp/test >> echo 2147483650 > /sys/fs/ext4/$disk/mb_group_prealloc >> echo test > /tmp/test/file && sync >> >> ================================================================== >> kernel BUG at fs/ext4/mballoc.c:2029! >> invalid opcode: 0000 [#1] PREEMPT SMP PTI >> CPU: 3 PID: 320 Comm: kworker/u36:1 Not tainted 6.8.0-rc1 #462 >> RIP: 0010:mb_mark_used+0x358/0x370 >> [...] >> Call Trace: >> ext4_mb_use_best_found+0x56/0x140 >> ext4_mb_complex_scan_group+0x196/0x2f0 >> ext4_mb_regular_allocator+0xa92/0xf00 >> ext4_mb_new_blocks+0x302/0xbc0 >> ext4_ext_map_blocks+0x95a/0xef0 >> ext4_map_blocks+0x2b1/0x680 >> ext4_do_writepages+0x733/0xbd0 >> [...] >> ================================================================== >> >> In ext4_mb_normalize_group_request(): >> ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc; >> >> Here fe_len is of type int, but s_mb_group_prealloc is of type unsigned >> int, so setting s_mb_group_prealloc to 2147483650 overflows fe_len to a >> negative number, which ultimately triggers a BUG_ON() in mb_mark_used(). >> >> Therefore, we add attr_pointer_pi (aka positive int attr pointer) with a >> value range of 0-INT_MAX to avoid the above problem. In addition to the >> mb_group_prealloc sysfs interface, the following interfaces also have uint >> to int conversions that result in overflows, and are also fixed. >> >> err_ratelimit_burst >> msg_ratelimit_burst >> warning_ratelimit_burst >> err_ratelimit_interval_ms >> msg_ratelimit_interval_ms >> warning_ratelimit_interval_ms >> mb_best_avail_max_trim_order >> >> CC: stable@vger.kernel.org >> Signed-off-by: Baokun Li > I don't think you need to change s_mb_group_prealloc here and then restrict > it even further in the next patch. I'd just leave it alone here. Yes, we could put the next patch before this one, but using s_mb_group_prealloc as an example makes it easier to understand why the attr_pointer_pi case is added here.There are several other variables that don't have more convincing examples. > > Also I think that limiting mb_best_avail_max_trim_order to 64 instead of > INT_MAX will make us more resilient to surprises in the future :) But I > don't really insist. > > Honza I think it's enough here to make sure that mb_best_avail_max_trim_order is a positive number, since we always make sure that min_order is not less than 0, as follows:          order = fls(ac->ac_g_ex.fe_len) - 1;          min_order = order - sbi->s_mb_best_avail_max_trim_order;          if (min_order < 0)                  min_order = 0; An oversized mb_best_avail_max_trim_order can be interpreted as always being CR_ANY_FREE. 😄 >> --- >> fs/ext4/sysfs.c | 25 +++++++++++++++++-------- >> 1 file changed, 17 insertions(+), 8 deletions(-) >> >> diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c >> index a5d657fa05cb..6f9f96e00f2f 100644 >> --- a/fs/ext4/sysfs.c >> +++ b/fs/ext4/sysfs.c >> @@ -30,6 +30,7 @@ typedef enum { >> attr_first_error_time, >> attr_last_error_time, >> attr_feature, >> + attr_pointer_pi, >> attr_pointer_ui, >> attr_pointer_ul, >> attr_pointer_u64, >> @@ -178,6 +179,9 @@ static struct ext4_attr ext4_attr_##_name = { \ >> #define EXT4_RO_ATTR_ES_STRING(_name,_elname,_size) \ >> EXT4_ATTR_STRING(_name, 0444, _size, ext4_super_block, _elname) >> >> +#define EXT4_RW_ATTR_SBI_PI(_name,_elname) \ >> + EXT4_ATTR_OFFSET(_name, 0644, pointer_pi, ext4_sb_info, _elname) >> + >> #define EXT4_RW_ATTR_SBI_UI(_name,_elname) \ >> EXT4_ATTR_OFFSET(_name, 0644, pointer_ui, ext4_sb_info, _elname) >> >> @@ -213,17 +217,17 @@ EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan); >> EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan); >> EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs); >> EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request); >> -EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc); >> +EXT4_RW_ATTR_SBI_PI(mb_group_prealloc, s_mb_group_prealloc); >> EXT4_RW_ATTR_SBI_UI(mb_max_linear_groups, s_mb_max_linear_groups); >> EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb); >> EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error); >> -EXT4_RW_ATTR_SBI_UI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval); >> -EXT4_RW_ATTR_SBI_UI(err_ratelimit_burst, s_err_ratelimit_state.burst); >> -EXT4_RW_ATTR_SBI_UI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval); >> -EXT4_RW_ATTR_SBI_UI(warning_ratelimit_burst, s_warning_ratelimit_state.burst); >> -EXT4_RW_ATTR_SBI_UI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval); >> -EXT4_RW_ATTR_SBI_UI(msg_ratelimit_burst, s_msg_ratelimit_state.burst); >> -EXT4_RW_ATTR_SBI_UI(mb_best_avail_max_trim_order, s_mb_best_avail_max_trim_order); >> +EXT4_RW_ATTR_SBI_PI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval); >> +EXT4_RW_ATTR_SBI_PI(err_ratelimit_burst, s_err_ratelimit_state.burst); >> +EXT4_RW_ATTR_SBI_PI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval); >> +EXT4_RW_ATTR_SBI_PI(warning_ratelimit_burst, s_warning_ratelimit_state.burst); >> +EXT4_RW_ATTR_SBI_PI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval); >> +EXT4_RW_ATTR_SBI_PI(msg_ratelimit_burst, s_msg_ratelimit_state.burst); >> +EXT4_RW_ATTR_SBI_PI(mb_best_avail_max_trim_order, s_mb_best_avail_max_trim_order); >> #ifdef CONFIG_EXT4_DEBUG >> EXT4_RW_ATTR_SBI_UL(simulate_fail, s_simulate_fail); >> #endif >> @@ -376,6 +380,7 @@ static ssize_t ext4_generic_attr_show(struct ext4_attr *a, >> >> switch (a->attr_id) { >> case attr_inode_readahead: >> + case attr_pointer_pi: >> case attr_pointer_ui: >> if (a->attr_ptr == ptr_ext4_super_block_offset) >> return sysfs_emit(buf, "%u\n", le32_to_cpup(ptr)); >> @@ -448,6 +453,10 @@ static ssize_t ext4_generic_attr_store(struct ext4_attr *a, >> return ret; >> >> switch (a->attr_id) { >> + case attr_pointer_pi: >> + if ((int)t < 0) >> + return -EINVAL; >> + fallthrough; >> case attr_pointer_ui: >> if (t != (unsigned int)t) >> return -EINVAL; >> -- >> 2.31.1 >> Thanks! -- With Best Regards, Baokun Li .