linux-kernel - RE: [PATCH] f2fs: do not allow to decompress files have FI_COMPRESS

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <25e501d8a6eb$84cf4090$8e6dc1b0$@samsung.com>
Date:   Wed, 3 Aug 2022 12:45:48 +0900
From:   "Sungjong Seo" <sj1557.seo@...sung.com>
To:     "'Jaewook Kim'" <jw5454.kim@...sung.com>, <jaegeuk@...nel.org>,
        <chao@...nel.org>
Cc:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <junbeom.yeom@...sung.com>,
        <youngjin.gil@...sung.com>, <sj1557.seo@...sung.com>
Subject: RE: [PATCH] f2fs: do not allow to decompress files have
 FI_COMPRESS_RELEASED

> If a file has FI_COMPRESS_RELEASED, all writes for it should not be
> allowed. However, as of now, in case of compress_mode=user, writes
> triggered by IOCTLs like F2FS_IOC_DE/COMPRESS_FILE are allowed unexpectly,
> which could crash that file.
> To fix it, let's do not allow F2FS_IOC_DE/COMPRESS_IOCTL if a file already
> has FI_COMPRESS_RELEASED flag.
> 
> This is the reproduction process:
> 1. $ chattr +c ./file
> 2. $ dd if=/dev/zero of=./file bs=4096 count=2000 oflag=append
> conv=notrunc 3. $ sync
> 4. $ do_compress ./file      ; call F2FS_IOC_COMPRESS_FILE
> 5. $ get_compr_blocks ./file ; call F2FS_IOC_GET_COMPRESS_BLOCKS

Oops! Do we need to call F2FS_IOC_RELEASE_COMPRESS_BLOCKS here?
Maybe, you need to revise reproduction process and to make v2 patch.

> 6. $ do_compress ./file      ; call F2FS_IOC_COMPRESS_FILE again
> 7. $ get_compr_blocks ./file ; call F2FS_IOC_GET_COMPRESS_BLOCKS again
> 
> You can find compr_blocks has a negative value.
> 
> Fixes: 5fdb322ff2c2b ("f2fs: add F2FS_IOC_DECOMPRESS_FILE and
> F2FS_IOC_COMPRESS_FILE")
> 
> Signed-off-by: Junbeom Yeom <junbeom.yeom@...sung.com>
> Signed-off-by: Sungjong Seo <sj1557.seo@...sung.com>
> Signed-off-by: Youngjin Gil <youngjin.gil@...sung.com>
> Signed-off-by: Jaewook Kim <jw5454.kim@...sung.com>
> ---
>  fs/f2fs/file.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index
> 6b1b030830ca..a4713b7e12cb 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -3945,6 +3945,11 @@ static int f2fs_ioc_decompress_file(struct file
> *filp, unsigned long arg)
>  		goto out;
>  	}
> 
> +	if (is_inode_flag_set(inode, FI_COMPRESS_RELEASED)) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
>  	ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
>  	if (ret)
>  		goto out;
> @@ -4012,6 +4017,11 @@ static int f2fs_ioc_compress_file(struct file *filp,
> unsigned long arg)
>  		goto out;
>  	}
> 
> +	if (is_inode_flag_set(inode, FI_COMPRESS_RELEASED)) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
>  	ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
>  	if (ret)
>  		goto out;
> --
> 2.17.1