On 2018/12/16 0:23, Richard Weinberger wrote:
> The rtime compressor assumes that at least two bytes are
> compressed.
> If we try to compress just one byte, the loop condition will
> wrap around and an out-of-bounds write happens.
>
> Cc: <sta...@vger.kernel.org>
> Signed-off-by: Richard Weinberger <rich...@nod.at>
> ---
> fs/jffs2/compr_rtime.c | 3 +++
> 1 file changed, 3 insertions(+)
> It seems that it doesn't incur any harm because the minimal allocated
size will be 8-bytes and jffs2_rtime_compress() will write 2-bytes into
the allocated buffer.
> diff --git a/fs/jffs2/compr_rtime.c b/fs/jffs2/compr_rtime.c
> index 406d9cc84ba8..cbf700001fc9 100644
> --- a/fs/jffs2/compr_rtime.c
> +++ b/fs/jffs2/compr_rtime.c
> @@ -39,6 +39,9 @@ static int jffs2_rtime_compress(unsigned char *data_in,
>
> memset(positions,0,sizeof(positions));
>
> + if (*dstlen < 2)
> + return -1;
> +
> while (pos < (*sourcelen) && outpos <= (*dstlen)-2) {
> int backpos, runlen=0;
> unsigned char value;
>
