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 790D3442C for ; Thu, 5 Jun 2025 03:31:38 +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=1749094298; cv=none; b=imbpQ6CVEgtcMsCL7bFg91zTqPFZfPRPHYrUhdChSfUoKcGADMJwTy+6g6g4vNTyn1xDM2stJC6peQQxrgGidA/FZlPCINjfDH4R3pshjy4h/A5FgVPfGJvLEuzUi3lbIZ6l3c7R3qTeLAhK33ZAYjtqjjqmb8YyN1V/P6C1xYQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749094298; c=relaxed/simple; bh=zD9KLdlxoxnlel0R+Dkuhh1beMBQe4Pg1pYX12Fw11w=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=fig8b4HHtIkjsjOxJmAusxOnxpn6kNqerI1sXj9sZ7c7fscZjmf0UZ6UfGUjb0kJGX6aMqGpqxVq5vo7EfsXjI6O+2RHP2nUB0ddjLMxI2dEEweLtRBo2GdtYFwl+vfEpwshYjqT5dre3y8dSzwbWBWochx0f4O7BrSkznmT3Mk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=N0mNAood; 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="N0mNAood" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 058F1C4CEEB; Thu, 5 Jun 2025 03:31:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749094298; bh=zD9KLdlxoxnlel0R+Dkuhh1beMBQe4Pg1pYX12Fw11w=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=N0mNAoodH8TxwIffoYAp4amYWbVnUShMldcW4shFI9Q/GpK8mGqNUXUYAktsr4ENm r1JuvnXsClo3jrA+Ytf96oIb9pwpDI3IBMQHKeWUZDKwMfnBmWMvEr2roh/G8XlE+z p2D1ae2GUomPL+GMpSywOWft13FqwUqVs2wKOUIMH0yPghuaEa6hszSQaA0wNSLYnI rYyhSUdgkrlgCOm4WcDIMy8QdsslayX00qr+oKJfLkojas6Uceey8+8aKRwhMsUuGZ 53D1yxHwsKlqY5hy+NBVMnR6XV7SrBDmHAjNL+cCGYRlD5NEQwldkdOLu9CMRznpRU UHEflhRf82O5g== Message-ID: <2a387dd6-9c10-478d-aae2-8284ad395944@kernel.org> Date: Thu, 5 Jun 2025 11:31:33 +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, Zhiguo Niu , jaegeuk@kernel.org, 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 v2] f2fs: compress: fix UAF of f2fs_inode_info in f2fs_free_dic To: Zhiguo Niu References: <1749037059-4243-1-git-send-email-zhiguo.niu@unisoc.com> <76adf905-191d-4415-a584-a79bc502bb87@kernel.org> Content-Language: en-US From: Chao Yu In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 6/5/25 10:44, Zhiguo Niu wrote: > Chao Yu 于2025年6月5日周四 10:23写道： >> >> On 6/4/25 19:37, 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 __iget before f2fs_free_dic and iput after free the dic. >>> >>> Cc: Daeho Jeong >>> Fixes: bff139b49d9f ("f2fs: handle decompress only post processing in softirq") >>> Signed-off-by: Zhiguo Niu >>> Signed-off-by: Baocong Liu >>> --- >>> v2: use __iget/iput function >>> --- >>> fs/f2fs/compress.c | 16 +++++++++++----- >>> 1 file changed, 11 insertions(+), 5 deletions(-) >>> >>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c >>> index b3c1df9..3f0c18d 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 +1785,20 @@ 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); >>> + /* to avoid inode is evicted simultaneously */ >>> + spin_lock(&dic->inode->i_lock); >>> + __iget(dic->inode); >>> + spin_unlock(&dic->inode->i_lock); >> >> Oh, how about using igrab() instead? > Hi Chao, > after I check igrab, I think it is ok, > but here We don't need care about igarb's return value, right? I guess "return NULL" should be impossible case, but still we can add f2fs_bug_on() to detect any potential bug, right? Thanks, > Thanks! > >> >>> queue_work(F2FS_I_SB(dic->inode)->post_read_wq, >>> &dic->free_work); >>> } >>