From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 709E9224DD for ; Tue, 16 Jul 2024 07:50:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721116202; cv=none; b=VvQhhmEscyIRd5eHCDBHNMZFIlWtlWvg+G3i4ZsrOIJjjEa976NqJlnPFsxLXvGEQRuf5xreZIsAuN33vQavpF/XnR7lEv+mItbHy+2Y2ptMkjlSbti7FanuORl5UExYGnx11T61ZMOMWxIyCih8S/Nm4qrvdG+NjU25KAZpb6M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721116202; c=relaxed/simple; bh=9WEOPNxxZLiUQpUPT3lCFVhiBuJN/xAzOgIHuyhfUZE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=L/mzHOQzd2Lee9sfAsYy2GuYESy0w4WnB+ZRBhY8+9fOAjgPaf4Cz47yNrsFFkTdCeLuEnm0UquvGQu4zFf6zdlrKcSBZFiQ3AQ7xYJOOEl2FSynbH3TJcnP8LZlZjMmTlbPu+bFPXLlVEmzQMhOr4dSiQKoKNkYa49HJPRSopE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CHT5CYEA; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CHT5CYEA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C75CC116B1; Tue, 16 Jul 2024 07:50:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1721116202; bh=9WEOPNxxZLiUQpUPT3lCFVhiBuJN/xAzOgIHuyhfUZE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=CHT5CYEAU6cu2uA+9GvMmzbQ/1Bi9sCm5k4Ayvw2+TH8Dby0iCQxZAvyHx1fWfEyi 5jqQ/4Su3h4tNycH6xPNey/Vu+excW5zUkPrfANRdaRxTxsQEnKxms+b+K7IbOnQ4j fFDj1nuvkfeTVtKp0t7r8R5Ih0cbc9hxBdqQcDm8= Date: Tue, 16 Jul 2024 09:49:59 +0200 From: Greg KH To: Baokun Li Cc: sashal@kernel.org, yangerkun@huawei.com, Jan Kara , Ojaswin Mujoo , Theodore Ts'o , stable@vger.kernel.org Subject: Re: [PATCH 6.6/6.9 v2 2/2] ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists() Message-ID: <2024071615-alienable-flirt-4ba6@gregkh> References: <20240619121952.3508695-1-libaokun@huaweicloud.com> <20240619121952.3508695-2-libaokun@huaweicloud.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Jul 16, 2024 at 10:11:55AM +0800, Baokun Li wrote: > On 2024/6/19 20:19, libaokun@huaweicloud.com wrote: > > From: Baokun Li > > > > [ Upstream commit 13df4d44a3aaabe61cd01d277b6ee23ead2a5206 ] > > > > 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. > > > > Add a new attr_id attr_clusters_in_group with values in the range > > [0, sbi->s_clusters_per_group] and declare mb_group_prealloc as > > that type to fix the issue. In addition avoid returning an order > > from mb_avg_fragment_size_order() greater than MB_NUM_ORDERS(sb) > > and reduce some useless loops. > > > > Fixes: 7e170922f06b ("ext4: Add allocation criteria 1.5 (CR1_5)") > > CC: stable@vger.kernel.org > > Signed-off-by: Baokun Li > > Reviewed-by: Jan Kara > > Reviewed-by: Ojaswin Mujoo > > Link: https://lore.kernel.org/r/20240319113325.3110393-5-libaokun1@huawei.com > > Signed-off-by: Theodore Ts'o > > Signed-off-by: Sasha Levin > > Signed-off-by: Baokun Li > > --- > > fs/ext4/mballoc.c | 4 ++++ > > fs/ext4/sysfs.c | 15 ++++++++++++++- > > 2 files changed, 18 insertions(+), 1 deletion(-) > > > > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > > index 714f83632e3f..66b5a68b0254 100644 > > --- a/fs/ext4/mballoc.c > > +++ b/fs/ext4/mballoc.c > > @@ -831,6 +831,8 @@ 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; > > } > > @@ -1008,6 +1010,8 @@ static void ext4_mb_choose_next_group_best_avail(struct ext4_allocation_context > > * goal length. > > */ > > order = fls(ac->ac_g_ex.fe_len) - 1; > > + if (WARN_ON_ONCE(order - 1 > MB_NUM_ORDERS(ac->ac_sb))) > > + order = MB_NUM_ORDERS(ac->ac_sb); > > min_order = order - sbi->s_mb_best_avail_max_trim_order; > > if (min_order < 0) > > min_order = 0; > > diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c > > index ca820620b974..d65dccb44ed5 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_clusters_in_group, > > attr_feature, > > attr_pointer_ui, > > attr_pointer_ul, > > @@ -207,13 +208,14 @@ 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, clusters_in_group, > > + 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_UI(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); > > @@ -392,6 +394,7 @@ static ssize_t ext4_attr_show(struct kobject *kobj, > > (unsigned long long) > > percpu_counter_sum(&sbi->s_sra_exceeded_retry_limit)); > > case attr_inode_readahead: > > + case attr_clusters_in_group: > > case attr_pointer_ui: > > if (!ptr) > > return 0; > > @@ -469,6 +472,16 @@ static ssize_t ext4_attr_store(struct kobject *kobj, > > else > > *((unsigned int *) ptr) = t; > > return len; > > + case attr_clusters_in_group: > > Hi Greg, > > > + if (!ptr) > > + return 0; > > I've found that the commit that eventually gets merged in doesn't have this > judgment. > > 6.6: 677ff4589f15 ("ext4: fix slab-out-of-bounds in > ext4_mb_find_good_group_avg_frag_lists()") > 6.9: b829687ae122 ("ext4: fix slab-out-of-bounds in > ext4_mb_find_good_group_avg_frag_lists()") > > This may result in a null pointer dereference. > > > History: > https://lore.kernel.org/all/0d620010-c6b4-4f80-a835-451813f957e3@huawei.com/ > https://lore.kernel.org/all/20240619121952.3508695-2-libaokun@huaweicloud.com/ > https://lore.kernel.org/all/20240625085542.189183696@linuxfoundation.org/ I don't understand, can you send a patch that fixes this? Or should we just revert the original commits? If so, what commit ids need to be reverted? thanks, greg k-h