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 7D303BA49 for ; Thu, 5 Jun 2025 02:23:58 +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=1749090238; cv=none; b=jEhBd7lf9HmJmBPXddqyckQuhFRgjcaE9vB8YU8bCx8Gphb1rKBGevUrqTXgEKMdj4Mi9FHE2YMXD3yWGx2qNgMes4jqFLDbyQkoamuuRvDLT8CjYM6RXn+MjwRRYLJSwGapdXEONuaw3o3BpaY7M54uELyTKRtPzveucCmVcdE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749090238; c=relaxed/simple; bh=/kcE555w9kFdV5l/AbRPGaf2+lFzCpzHbueTVlIUK+0=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=sP4cP37g5nUNoePUP9KqPIrjD7tVOy4GSTU0kdHkMXPA/SCoRODO9Q+UZcdAEndwCQTo9AuNp4E8xshHkQwodU8MeF2L6SS4LUjy5Jgd8hrPtQCtkH7yB0bc5+KoagpQ3Dcag/uRPUx4/eImmRjZ2CS1kVa+LMaTvbdcZf5nJQE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bGAx2nZP; 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="bGAx2nZP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0708AC4CEE4; Thu, 5 Jun 2025 02:23:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749090237; bh=/kcE555w9kFdV5l/AbRPGaf2+lFzCpzHbueTVlIUK+0=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=bGAx2nZPo/ajfn9KlbrYt473bL1oTK6so6RMy1Yds3rZrSP9uIuHsP3aq+f9vxgl2 wrUZAXhq7uryrXLXt8Jb5limPaFtfqNRxPU3PG+eoGNhoVVHn0CFUBVvmkAIdDsMW5 DYqERjxSW6l3fLVbP7P6d/AqVRH915liUmGv+2le3ACKRPyBR2tQ2stO2YA52D6+/8 ThYLyuieORgaWQF86u16jraYgYOSq5mtdCB3cx5KpkMwwpox6UP04BUoFWZkArOCsD vnsCSLpVwoSSGiNGULCRJcoQmM/S6dI0Cqkfk3jCCGUpCuE5bOVJvh/gizYFQHwE0i cW98ehacEXsjw== Message-ID: <76adf905-191d-4415-a584-a79bc502bb87@kernel.org> Date: Thu, 5 Jun 2025 10:23:53 +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, linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, niuzhiguo84@gmail.com, 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 , jaegeuk@kernel.org References: <1749037059-4243-1-git-send-email-zhiguo.niu@unisoc.com> Content-Language: en-US From: Chao Yu In-Reply-To: <1749037059-4243-1-git-send-email-zhiguo.niu@unisoc.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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? > queue_work(F2FS_I_SB(dic->inode)->post_read_wq, > &dic->free_work); > }