linux-kernel - [PATCH 5.18 0955/1095] f2fs: do not allow to decompress files have FI_COMPRESS

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Date:   Mon, 15 Aug 2022 20:05:54 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Junbeom Yeom <junbeom.yeom@...sung.com>,
        Sungjong Seo <sj1557.seo@...sung.com>,
        Youngjin Gil <youngjin.gil@...sung.com>,
        Jaewook Kim <jw5454.kim@...sung.com>,
        Chao Yu <chao@...nel.org>, Jaegeuk Kim <jaegeuk@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.18 0955/1095] f2fs: do not allow to decompress files have FI_COMPRESS_RELEASED

From: Jaewook Kim <jw5454.kim@...sung.com>

[ Upstream commit 90be48bd9d29ece3965e5e8b21499b6db166e57b ]

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.  $ touch ./file
2.  $ chattr +c ./file
3.  $ dd if=/dev/random of=./file bs=4096 count=30 conv=notrunc
4.  $ dd if=/dev/zero of=./file bs=4096 count=34 seek=30 conv=notrunc
5.  $ sync
6.  $ do_compress ./file      ; call F2FS_IOC_COMPRESS_FILE
7.  $ get_compr_blocks ./file ; call F2FS_IOC_GET_COMPRESS_BLOCKS
8.  $ release ./file          ; call F2FS_IOC_RELEASE_COMPRESS_BLOCKS
9.  $ do_compress ./file      ; call F2FS_IOC_COMPRESS_FILE again
10. $ get_compr_blocks ./file ; call F2FS_IOC_GET_COMPRESS_BLOCKS again

This reproduction process is tested in 128kb cluster size.
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>
Reviewed-by: Chao Yu <chao@...nel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/f2fs/file.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 9a676ea080e4..c2644a085876 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3914,6 +3914,11 @@ 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;
@@ -3981,6 +3986,11 @@ 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;
-- 
2.35.1