Re: [PATCH v2] f2fs: do not allow to decompress files have FI_COMPRESS_RELEASED

[Chao Yu]

On 2022/8/3 16:53, Jaewook Kim wrote:
> 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@xxxxxxxxxxx>
> Signed-off-by: Sungjong Seo <sj1557.seo@xxxxxxxxxxx>
> Signed-off-by: Youngjin Gil <youngjin.gil@xxxxxxxxxxx>
> Signed-off-by: Jaewook Kim <jw5454.kim@xxxxxxxxxxx>

Reviewed-by: Chao Yu <chao@xxxxxxxxxx>

Thanks,