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Commit 3ac18232 authored by Tim Gardner's avatar Tim Gardner Committed by Daniel Vetter
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i915: intel_set_mode: Reduce stack allocation from 500 bytes to 2 pointers 



smatch warning:

drivers/gpu/drm/i915/intel_display.c:7019 intel_set_mode() warn: function puts
500 bytes on stack

Refactor so that saved_mode and saved_hwmode are dynamically allocated as opposed
to being automatic variables. 500 bytes seems like it could run the potential for blowing
the kernel stack.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: default avatarTim Gardner <tim.gardner@canonical.com>
Reviewed-by: default avatarJani Nikula <jani.nikula@intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 378a6a77

drivers/gpu/drm/i915/intel_display.c

+16 −6
Original line number Original line Diff line number Diff line
@@ -7398,11 +7398,18 @@ bool intel_set_mode(struct drm_crtc *crtc, 
{

{

	struct drm_device *dev = crtc->dev;

	struct drm_device *dev = crtc->dev;

	drm_i915_private_t *dev_priv = dev->dev_private;

	drm_i915_private_t *dev_priv = dev->dev_private;

	struct drm_display_mode *adjusted_mode, saved_mode, saved_hwmode;

	struct drm_display_mode *adjusted_mode, *saved_mode, *saved_hwmode;

	struct intel_crtc *intel_crtc;

	struct intel_crtc *intel_crtc;

	unsigned disable_pipes, prepare_pipes, modeset_pipes;

	unsigned disable_pipes, prepare_pipes, modeset_pipes;

	bool ret = true;

	bool ret = true;





	saved_mode = kmalloc(2 * sizeof(*saved_mode), GFP_KERNEL);

	if (!saved_mode) {

		DRM_ERROR("i915: Could not allocate saved display mode.\n");

		return false;

	}

	saved_hwmode = saved_mode + 1;



	intel_modeset_affected_pipes(crtc, &modeset_pipes,

	intel_modeset_affected_pipes(crtc, &modeset_pipes,

				     &prepare_pipes, &disable_pipes);

				     &prepare_pipes, &disable_pipes);
@@ -7412,8 +7419,8 @@ bool intel_set_mode(struct drm_crtc *crtc, 
	for_each_intel_crtc_masked(dev, disable_pipes, intel_crtc)

	for_each_intel_crtc_masked(dev, disable_pipes, intel_crtc)

		intel_crtc_disable(&intel_crtc->base);

		intel_crtc_disable(&intel_crtc->base);





	saved_hwmode = crtc->hwmode;

	*saved_hwmode = crtc->hwmode;

	saved_mode = crtc->mode;

	*saved_mode = crtc->mode;





	/* Hack: Because we don't (yet) support global modeset on multiple

	/* Hack: Because we don't (yet) support global modeset on multiple

	 * crtcs, we don't keep track of the new mode for more than one crtc.

	 * crtcs, we don't keep track of the new mode for more than one crtc.
@@ -7424,7 +7431,8 @@ bool intel_set_mode(struct drm_crtc *crtc, 
	if (modeset_pipes) {

	if (modeset_pipes) {

		adjusted_mode = intel_modeset_adjusted_mode(crtc, mode);

		adjusted_mode = intel_modeset_adjusted_mode(crtc, mode);

		if (IS_ERR(adjusted_mode)) {

		if (IS_ERR(adjusted_mode)) {

			return false;

			ret = false;

			goto out;

		}

		}

	}

	}
@@ -7476,12 +7484,14 @@ bool intel_set_mode(struct drm_crtc *crtc, 
done:

done:

	drm_mode_destroy(dev, adjusted_mode);

	drm_mode_destroy(dev, adjusted_mode);

	if (!ret && crtc->enabled) {

	if (!ret && crtc->enabled) {

		crtc->hwmode = saved_hwmode;

		crtc->hwmode = *saved_hwmode;

		crtc->mode = saved_mode;

		crtc->mode = *saved_mode;

	} else {

	} else {

		intel_modeset_check_state(dev);

		intel_modeset_check_state(dev);

	}

	}





out:

	kfree(saved_mode);

	return ret;

	return ret;

}

}