Re: [PATCH i-g-t] kms_cursor_crc: Kernel now checks for integer overflow

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 03 Feb 2015, Matt Roper <matthew.d.roper@intel.com> wrote:
> As of kernel commit
>
>     commit a679064a7e9e8799177a64a31668a34a1bc6a4f1
>     Author: Matt Roper <matthew.d.roper@intel.com>
>     Date:   Fri Jan 30 16:22:37 2015 -0800
>
>         drm/i915: Switch planes from transitional helpers to full atomic helpers
>
> the kernel now checks for cursor coordinates that would result in
> integer overflow and returns -ERANGE, similar to the checking that was
> already done for other plane types.  We update kms_cursor_crc here to
> reflect this small behavior change:
>  * Check for success at extreme boundary conditions INT_MAX-{width,height}
>    rather than INT_MAX
>  * Add new check for success at SHRT_MAX; if the driver were to
>    internally use short values and overflow, we could have the cursor
>    reappear on the screen.
>  * Add a test for failure with proper error code at INT_MAX-{width,height}+1
>
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>


Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88917

?


> ---
>  tests/kms_cursor_crc.c | 29 ++++++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/tests/kms_cursor_crc.c b/tests/kms_cursor_crc.c
> index e1390a7..64fea12 100644
> --- a/tests/kms_cursor_crc.c
> +++ b/tests/kms_cursor_crc.c
> @@ -139,6 +139,29 @@ static void do_single_test(data_t *data, int x, int y)
>  	igt_assert(igt_crc_equal(&crc, &ref_crc));
>  }
>  
> +static void do_fail_test(data_t *data, int x, int y, int expect)
> +{
> +	igt_display_t *display = &data->display;
> +	igt_plane_t *cursor;
> +	cairo_t *cr = igt_get_cairo_ctx(data->drm_fd, &data->primary_fb);
> +	int ret;
> +
> +	igt_print_activity();
> +
> +	/* Hardware test */
> +	igt_paint_test_pattern(cr, data->screenw, data->screenh);
> +	cursor_enable(data);
> +	cursor = igt_output_get_plane(data->output, IGT_PLANE_CURSOR);
> +	igt_plane_set_position(cursor, x, y);
> +	ret = igt_display_try_commit2(display, COMMIT_LEGACY);
> +
> +	igt_plane_set_position(cursor, 0, 0);
> +	cursor_disable(data);
> +	igt_display_commit(display);
> +
> +	igt_assert(ret == expect);
> +}
> +
>  static void do_test(data_t *data,
>  		    int left, int right, int top, int bottom)
>  {
> @@ -201,7 +224,11 @@ static void test_crc_offscreen(data_t *data)
>  	do_test(data, left - (cursor_w+512), right + (cursor_w+512), top - (cursor_h+512), bottom + (cursor_h+512));
>  
>  	/* go nuts */
> -	do_test(data, INT_MIN, INT_MAX, INT_MIN, INT_MAX);
> +	do_test(data, INT_MIN, INT_MAX - cursor_w, INT_MIN, INT_MAX - cursor_h);
> +	do_test(data, SHRT_MIN, SHRT_MAX, SHRT_MIN, SHRT_MAX);
> +
> +	/* Make sure we get -ERANGE on integer overflow */
> +	do_fail_test(data, INT_MAX - cursor_w + 1, INT_MAX - cursor_h + 1, -ERANGE);
>  }
>  
>  static void test_crc_sliding(data_t *data)
> -- 
> 1.8.5.1
>
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-- 
Jani Nikula, Intel Open Source Technology Center
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