From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) (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 EF642208B4; Sat, 27 Jan 2024 02:09:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706321390; cv=none; b=mrzsv6o4c2+7/noVQzjkjdLo2qhdLdVrjNrPAocv/lZdYsJAyklksM876hOY7QhBvtBXOCx7i5hHhsSalSWL05z/wp47tb7AEmvOaLAYT29UykZLgRn4S1QXumq67eGXyV3ztdJlzM5RguLAhWiMhSZT9oFvleMmlmxWnBq2rGY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706321390; c=relaxed/simple; bh=+pYx7ft3ahDQObB+uMHot6yq1CCxImD8uNkp8sb71dk=; h=Subject:To:CC:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=awTtJeJZlGQq83G5dqhGD/m+0/3wTtrHek4eQiXlVP3sTrFFKneU/dkS60UowoWD21SPclqbAiGbmyQxEkTFUaLgVnCcK+Q9qIX6GFZYWFXEbnpkuaOupYfW6dV3y+otogc+kGs1OCWJb6wwGtGt2A4T12GNa2EXOYk8krWBRyY= 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=45.249.212.188 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 [172.19.163.48]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4TMHzC273rzXgnv; Sat, 27 Jan 2024 10:08:23 +0800 (CST) Received: from canpemm500005.china.huawei.com (unknown [7.192.104.229]) by mail.maildlp.com (Postfix) with ESMTPS id 8E1F518006C; Sat, 27 Jan 2024 10:09:39 +0800 (CST) Received: from [10.174.176.34] (10.174.176.34) by canpemm500005.china.huawei.com (7.192.104.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Sat, 27 Jan 2024 10:09:38 +0800 Subject: Re: [PATCH 5/7] ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists() To: Baokun Li , CC: , , , , , , , , References: <20240126085716.1363019-1-libaokun1@huawei.com> <20240126085716.1363019-6-libaokun1@huawei.com> From: Zhang Yi Message-ID: <8014855d-7f8c-9bf9-3390-8c9973007ed2@huawei.com> Date: Sat, 27 Jan 2024 10:09:38 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20240126085716.1363019-6-libaokun1@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To canpemm500005.china.huawei.com (7.192.104.229) On 2024/1/26 16:57, Baokun Li wrote: > We can trigger a slab-out-of-bounds with the following commands: > > mkfs.ext4 -F /dev/$disk 10G > mount /dev/$disk /tmp/test > echo 2147483647 > /sys/fs/ext4/$disk/mb_group_prealloc > echo test > /tmp/test/file && sync > > ================================================================== > BUG: KASAN: slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] > Read of size 8 at addr ffff888121b9d0f0 by task kworker/u2:0/11 > CPU: 0 PID: 11 Comm: kworker/u2:0 Tainted: GL 6.7.0-next-20240118 #521 > Call Trace: > dump_stack_lvl+0x2c/0x50 > kasan_report+0xb6/0xf0 > ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] > ext4_mb_regular_allocator+0x19e9/0x2370 [ext4] > ext4_mb_new_blocks+0x88a/0x1370 [ext4] > ext4_ext_map_blocks+0x14f7/0x2390 [ext4] > ext4_map_blocks+0x569/0xea0 [ext4] > ext4_do_writepages+0x10f6/0x1bc0 [ext4] > [...] > ================================================================== > > The flow of issue triggering is as follows: > > // Set s_mb_group_prealloc to 2147483647 via sysfs > ext4_mb_new_blocks > ext4_mb_normalize_request > ext4_mb_normalize_group_request > ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc > ext4_mb_regular_allocator > ext4_mb_choose_next_group > ext4_mb_choose_next_group_best_avail > mb_avg_fragment_size_order > order = fls(len) - 2 = 29 > ext4_mb_find_good_group_avg_frag_lists > frag_list = &sbi->s_mb_avg_fragment_size[order] > if (list_empty(frag_list)) // Trigger SOOB! > > At 4k block size, the length of the s_mb_avg_fragment_size list is 14, but > an oversized s_mb_group_prealloc is set, causing slab-out-of-bounds to be > triggered by an attempt to access an element at index 29. > > Therefore it is not allowed to set s_mb_group_prealloc to a value greater > than s_clusters_per_group via sysfs, and to avoid returning an order from > mb_avg_fragment_size_order() that is greater than MB_NUM_ORDERS(sb). > > Fixes: 7e170922f06b ("ext4: Add allocation criteria 1.5 (CR1_5)") > CC: stable@vger.kernel.org > Signed-off-by: Baokun Li Looks good to me. Reviewed-by: Zhang Yi > --- > fs/ext4/mballoc.c | 2 ++ > fs/ext4/sysfs.c | 9 ++++++++- > 2 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > index f44f668e407f..1ea6491b6b00 100644 > --- a/fs/ext4/mballoc.c > +++ b/fs/ext4/mballoc.c > @@ -832,6 +832,8 @@ static int mb_avg_fragment_size_order(struct super_block *sb, ext4_grpblk_t len) > return 0; > if (order == MB_NUM_ORDERS(sb)) > order--; > + if (WARN_ON_ONCE(order > MB_NUM_ORDERS(sb))) > + order = MB_NUM_ORDERS(sb) - 1; > return order; > } > > diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c > index 6f9f96e00f2f..60ca7b2797b2 100644 > --- a/fs/ext4/sysfs.c > +++ b/fs/ext4/sysfs.c > @@ -29,6 +29,7 @@ typedef enum { > attr_trigger_test_error, > attr_first_error_time, > attr_last_error_time, > + attr_group_prealloc, > attr_feature, > attr_pointer_pi, > attr_pointer_ui, > @@ -211,13 +212,14 @@ EXT4_ATTR_FUNC(sra_exceeded_retry_limit, 0444); > > EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, inode_readahead, > ext4_sb_info, s_inode_readahead_blks); > +EXT4_ATTR_OFFSET(mb_group_prealloc, 0644, group_prealloc, > + ext4_sb_info, s_mb_group_prealloc); > EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal); > EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats); > 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_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); > @@ -380,6 +382,7 @@ static ssize_t ext4_generic_attr_show(struct ext4_attr *a, > > switch (a->attr_id) { > case attr_inode_readahead: > + case attr_group_prealloc: > case attr_pointer_pi: > case attr_pointer_ui: > if (a->attr_ptr == ptr_ext4_super_block_offset) > @@ -453,6 +456,10 @@ static ssize_t ext4_generic_attr_store(struct ext4_attr *a, > return ret; > > switch (a->attr_id) { > + case attr_group_prealloc: > + if (t > sbi->s_clusters_per_group) > + return -EINVAL; > + fallthrough; > case attr_pointer_pi: > if ((int)t < 0) > return -EINVAL; >