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 19D861AAC9 for ; Wed, 11 Jun 2025 06:47:20 +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=1749624442; cv=none; b=PawQH1pWZKJ6xFavniazScy3V56Zla/daR9bCso460FL+weHGKkgdj0PtAFKsdQ+Lep+hUOaRHoDaHl/xIVR8352hI6KtVMiNzwwszcBYNduiFNKTvUSCzB42JtPORrzGjKLNioGVapjbzmD+cifvr8b6MroRPy65JZ8EB+2JQ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749624442; c=relaxed/simple; bh=Y7drl0N8DpxbEGHn/GNhO4IXTOkaEABM7Sc5vcplQJc=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=EYuyOaHKHk6K1x+8IP0oiiC9fxgCp6eHqp8XEodsT/+PY6hLDgj6dZB7d9wuxcgqWpZ1fLiDkYOoLlgP5tzxCgytRie3rgmP8iaabQ82WU8YhClatO4CKYwHGBMAZjdAwHsPJ1PgOrvP3rbsTAn+Ob3hDiuuSMbtwsH0+0WHpek= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Mmpf0N/j; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Mmpf0N/j" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B1645C4CEEE; Wed, 11 Jun 2025 06:47:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749624440; bh=Y7drl0N8DpxbEGHn/GNhO4IXTOkaEABM7Sc5vcplQJc=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=Mmpf0N/jNItTtSVV77cphUJ/VJl9iiHKOY9t1mlUoEpfBGhZ6qc2f1NcxprXCXQWH Uxitl070VC7uObSKvmZD/AEOEHLnpJVjplpq1CqzRlf0/chl9ubs0lWxp47D1Cyzss ly/OcVZJOM8yLN8Y15Aqxx0qNCNxFRgp+4jXSghZybMS1JaT8F7cFTbEaOtrPAXuUT eBZsA7/MdZop6TmaK9MlMik7tWMVU1l3u2hYdc4Eyp6yGowi2dCv6dunvNKm3CvNF+ xVqfhi4CZqqc3zPM96F7u4uxc2ExkGc6KNkiixQH5hnyAeQ5RztRYEn35r+WVRT4S1 Fja9ZOqLe1IBw== Message-ID: Date: Wed, 11 Jun 2025 14:47:14 +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 Cc: chao@kernel.org, Jaegeuk Kim , Zhiguo Niu , linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, ke.wang@unisoc.com, Hao_hao.Wang@unisoc.com, baocong.liu@unisoc.com Subject: Re: [PATCH v3] f2fs: compress: fix UAF of f2fs_inode_info in f2fs_free_dic To: Zhiguo Niu References: <1749107920-17958-1-git-send-email-zhiguo.niu@unisoc.com> <5c1da066-0c76-42f4-8c46-a99f60a900bf@kernel.org> Content-Language: en-US From: Chao Yu In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 6/11/25 14:41, Zhiguo Niu wrote: > Chao Yu 于2025年6月11日周三 14:07写道： >> >> On 6/11/25 00:08, Jaegeuk Kim wrote: >>> Hi Zhiguo, >>> >>> This patch causes CPU hang when running fsstress on compressed/non-compressed >>> files. Please check. >> >> Oh, seems it may cause below deadlock: >> >> CPU0 >> process A >> - spin_lock(i_lock) >> software IRQ >> - end_io >> - igrab >> - spin_lock(i_lock) >> >> Thanks, > Hi Chao, > Thanks for pointing this out. > I have tested this patch locally about some basic cases before submission. > So it seems that should use the following method to solve this problem? > " store i_compress_algorithm/sbi in dic to avoid inode access?" Zhiguo, Yeah, I guess so. Thanks, > thanks！ > > >> >>> >>> On 06/05, Zhiguo Niu wrote: >>>> The decompress_io_ctx may be released asynchronously after >>>> I/O completion. If this file is deleted immediately after read, >>>> and the kworker of processing post_read_wq has not been executed yet >>>> due to high workloads, It is possible that the inode(f2fs_inode_info) >>>> is evicted and freed before it is used f2fs_free_dic. >>>> >>>> The UAF case as below: >>>> Thread A Thread B >>>> - f2fs_decompress_end_io >>>> - f2fs_put_dic >>>> - queue_work >>>> add free_dic work to post_read_wq >>>> - do_unlink >>>> - iput >>>> - evict >>>> - call_rcu >>>> This file is deleted after read. >>>> >>>> Thread C kworker to process post_read_wq >>>> - rcu_do_batch >>>> - f2fs_free_inode >>>> - kmem_cache_free >>>> inode is freed by rcu >>>> - process_scheduled_works >>>> - f2fs_late_free_dic >>>> - f2fs_free_dic >>>> - f2fs_release_decomp_mem >>>> read (dic->inode)->i_compress_algorithm >>>> >>>> This patch use igrab before f2fs_free_dic and iput after free the dic when dic free >>>> action is done by kworker. >>>> >>>> Cc: Daeho Jeong >>>> Fixes: bff139b49d9f ("f2fs: handle decompress only post processing in softirq") >>>> Signed-off-by: Zhiguo Niu >>>> Signed-off-by: Baocong Liu >>>> --- >>>> v3: use igrab to replace __iget >>>> v2: use __iget/iput function >>>> --- >>>> fs/f2fs/compress.c | 14 +++++++++----- >>>> 1 file changed, 9 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c >>>> index b3c1df9..729ad16 100644 >>>> --- a/fs/f2fs/compress.c >>>> +++ b/fs/f2fs/compress.c >>>> @@ -1687,7 +1687,7 @@ static void f2fs_release_decomp_mem(struct decompress_io_ctx *dic, >>>> } >>>> >>>> static void f2fs_free_dic(struct decompress_io_ctx *dic, >>>> - bool bypass_destroy_callback); >>>> + bool bypass_destroy_callback, bool late_free); >>>> >>>> struct decompress_io_ctx *f2fs_alloc_dic(struct compress_ctx *cc) >>>> { >>>> @@ -1743,12 +1743,12 @@ struct decompress_io_ctx *f2fs_alloc_dic(struct compress_ctx *cc) >>>> return dic; >>>> >>>> out_free: >>>> - f2fs_free_dic(dic, true); >>>> + f2fs_free_dic(dic, true, false); >>>> return ERR_PTR(ret); >>>> } >>>> >>>> static void f2fs_free_dic(struct decompress_io_ctx *dic, >>>> - bool bypass_destroy_callback) >>>> + bool bypass_destroy_callback, bool late_free) >>>> { >>>> int i; >>>> >>>> @@ -1775,6 +1775,8 @@ static void f2fs_free_dic(struct decompress_io_ctx *dic, >>>> } >>>> >>>> page_array_free(dic->inode, dic->rpages, dic->nr_rpages); >>>> + if (late_free) >>>> + iput(dic->inode); >>>> kmem_cache_free(dic_entry_slab, dic); >>>> } >>>> >>>> @@ -1783,16 +1785,18 @@ static void f2fs_late_free_dic(struct work_struct *work) >>>> struct decompress_io_ctx *dic = >>>> container_of(work, struct decompress_io_ctx, free_work); >>>> >>>> - f2fs_free_dic(dic, false); >>>> + f2fs_free_dic(dic, false, true); >>>> } >>>> >>>> static void f2fs_put_dic(struct decompress_io_ctx *dic, bool in_task) >>>> { >>>> if (refcount_dec_and_test(&dic->refcnt)) { >>>> if (in_task) { >>>> - f2fs_free_dic(dic, false); >>>> + f2fs_free_dic(dic, false, false); >>>> } else { >>>> INIT_WORK(&dic->free_work, f2fs_late_free_dic); >>>> + /* use igrab to avoid inode is evicted simultaneously */ >>>> + f2fs_bug_on(F2FS_I_SB(dic->inode), !igrab(dic->inode)); >>>> queue_work(F2FS_I_SB(dic->inode)->post_read_wq, >>>> &dic->free_work); >>>> } >>>> -- >>>> 1.9.1 >>