[PATCH libXi] Fix invalid read in XIGrabDevice.

[Julien Cristau]

On Wed, Feb 23, 2011 at 09:36:06 +1000, Peter Hutterer wrote:

> Miscalculation of length caused Data() to memcpy too many bytes.
> 
> ==2865== Invalid read of size 1
> ==2865==    at 0x4A07480: memcpy (mc_replace_strmem.c:602)
> ==2865==    by 0x544271E: XIGrabDevice (XIGrabDevice.c:69)
> ==2865==    by 0x400B0A: main (gnome642481.c:56)
> ==2865==  Address 0x642f614 is 0 bytes after a block of size 20 alloc'd
> ==2865==    at 0x4A04896: calloc (vg_replace_malloc.c:418)
> ==2865==    by 0x54425D3: XIGrabDevice (XIGrabDevice.c:65)
> ==2865==    by 0x400B0A: main (gnome642481.c:56)
> 
> SetReqLen() expects 4-byte units.
> Data() expects bytes.
> 
> Gnome Bug 642481 <https://bugzilla.gnome.org/show_bug.cgi?id=642481>
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> ---
> 
>  src/XIGrabDevice.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/src/XIGrabDevice.c b/src/XIGrabDevice.c
> index 985d3f1..97ab971 100644
> --- a/src/XIGrabDevice.c
> +++ b/src/XIGrabDevice.c
> @@ -61,8 +61,8 @@ XIGrabDevice(Display* dpy, int deviceid, Window grab_window, Time time,
>  
>      /* masks.mask_len is in bytes, but we need 4-byte units on the wire,

typo here (masks → mask)

>       * and they need to be padded with 0 */
> -    len = req->mask_len * 4;
> -    buff = calloc(1, len);
> +    len = req->mask_len;
> +    buff = calloc(1, len * 4);
>      memcpy(buff, mask->mask, mask->mask_len);
>  
>      SetReqLen(req, len, len);

Reviewed-by: Julien Cristau <jcristau at debian.org>

Cheers,
Julien