On Fri, 07 Dec 2012, Tim Gardner <tim.gardner@xxxxxxxxxxxxx> 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@xxxxxxxxx>
>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxx>
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Tim Gardner <tim.gardner@xxxxxxxxxxxxx>
> ---
>
> 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
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