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    Subject[PATCH 5.15 665/779] f2fs: do not allow to decompress files have FI_COMPRESS_RELEASED
    Date
    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 0669464a942a..758048a885d2 100644
    --- a/fs/f2fs/file.c
    +++ b/fs/f2fs/file.c
    @@ -4011,6 +4011,11 @@ 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;
    @@ -4078,6 +4083,11 @@ 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


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