[PATCH 5.18 0955/1095] f2fs: do not allow to decompress files have FI_COMPRESS_RELEASED

Greg Kroah-Hartman
2022-08-15T23:07:52Z

From: Jaewook Kim <jw5454.kim@samsung.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@samsung.com>
Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Youngjin Gil <youngjin.gil@samsung.com>
Signed-off-by: Jaewook Kim <jw5454.kim@samsung.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.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