Re: [PATCH v2] fbdev: potential information leak in do_fb_ioctl()

2020-01-15 Thread Bartlomiej Zolnierkiewicz


On 1/13/20 12:08 PM, Dan Carpenter wrote:
> The "fix" struct has a 2 byte hole after ->ywrapstep and the
> "fix = info->fix;" assignment doesn't necessarily clear it.  It depends
> on the compiler.  The solution is just to replace the assignment with an
> memcpy().
> 
> Fixes: 1f5e31d7e55a ("fbmem: don't call copy_from/to_user() with mutex held")
> Signed-off-by: Dan Carpenter 

Patch queued for v5.6, thanks.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R Institute Poland
Samsung Electronics

> ---
> v2:  Use memcpy()
> 
>  drivers/video/fbdev/core/fbmem.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/video/fbdev/core/fbmem.c 
> b/drivers/video/fbdev/core/fbmem.c
> index d04554959ea7..bb8d8dbc0461 100644
> --- a/drivers/video/fbdev/core/fbmem.c
> +++ b/drivers/video/fbdev/core/fbmem.c
> @@ -1115,7 +1115,7 @@ static long do_fb_ioctl(struct fb_info *info, unsigned 
> int cmd,
>   break;
>   case FBIOGET_FSCREENINFO:
>   lock_fb_info(info);
> - fix = info->fix;
> + memcpy(, >fix, sizeof(fix));
>   if (info->flags & FBINFO_HIDE_SMEM_START)
>   fix.smem_start = 0;
>   unlock_fb_info(info);
> 
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[PATCH v2] fbdev: potential information leak in do_fb_ioctl()

2020-01-13 Thread Dan Carpenter
The "fix" struct has a 2 byte hole after ->ywrapstep and the
"fix = info->fix;" assignment doesn't necessarily clear it.  It depends
on the compiler.  The solution is just to replace the assignment with an
memcpy().

Fixes: 1f5e31d7e55a ("fbmem: don't call copy_from/to_user() with mutex held")
Signed-off-by: Dan Carpenter 
---
v2:  Use memcpy()

 drivers/video/fbdev/core/fbmem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index d04554959ea7..bb8d8dbc0461 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1115,7 +1115,7 @@ static long do_fb_ioctl(struct fb_info *info, unsigned 
int cmd,
break;
case FBIOGET_FSCREENINFO:
lock_fb_info(info);
-   fix = info->fix;
+   memcpy(, >fix, sizeof(fix));
if (info->flags & FBINFO_HIDE_SMEM_START)
fix.smem_start = 0;
unlock_fb_info(info);
-- 
2.11.0

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