On Fri, 07 Dec 2012, Tim Gardner tim.gardner@canonical.com wrote:

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.

Reviewed-by: Jani Nikula jani.nikula@intel.com

Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: David Airlie airlied@linux.ie Cc: dri-devel@lists.freedesktop.org Signed-off-by: Tim Gardner tim.gardner@canonical.com

---

V2 - spaces around '*', use kmalloc instead of kzalloc(). Missed error return that would have orphaned memory.

drivers/gpu/drm/i915/intel_display.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index de51489..c15b21b 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -7739,11 +7739,18 @@ bool intel_set_mode(struct drm_crtc *crtc, { struct drm_device *dev = crtc->dev; 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; unsigned disable_pipes, prepare_pipes, modeset_pipes; 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, &prepare_pipes, &disable_pipes);

@@ -7753,8 +7760,8 @@ bool intel_set_mode(struct drm_crtc *crtc, for_each_intel_crtc_masked(dev, disable_pipes, intel_crtc) intel_crtc_disable(&intel_crtc->base);

• saved_hwmode = crtc->hwmode;
• saved_mode = crtc->mode;

• *saved_hwmode = crtc->hwmode;

• *saved_mode = crtc->mode;

  /* 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.

@@ -7765,7 +7772,8 @@ bool intel_set_mode(struct drm_crtc *crtc, if (modeset_pipes) { adjusted_mode = intel_modeset_adjusted_mode(crtc, mode); if (IS_ERR(adjusted_mode)) {

• 	return false;
  

• 	ret = false;
  

• 	goto out;
  

  } }

@@ -7817,12 +7825,14 @@ bool intel_set_mode(struct drm_crtc *crtc, done: drm_mode_destroy(dev, adjusted_mode); if (!ret && crtc->enabled) {

• crtc->hwmode = saved_hwmode;
  

• crtc->mode = saved_mode;
  

• crtc->hwmode = *saved_hwmode;
  

• crtc->mode = *saved_mode;
  

  } else { intel_modeset_check_state(dev); }

+out:

• kfree(saved_mode); return ret;

}

-- 1.7.9.5