lkml.org 
[lkml]   [2018]   [Dec]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] jffs2: Fix integer underflow in jffs2_rtime_compress
From
Date


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: <stable@vger.kernel.org>
> Signed-off-by: Richard Weinberger <richard@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;
>

\
 
 \ /
  Last update: 2018-12-20 11:44    [W:0.063 / U:2.292 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site