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Subject[PATCH] drm/i915: Increase the amount of defense before computing vblank timestamps
Date
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---

Chris, does this help?

If you can convert the address to a line number that would pinpoint the
NULL pointer exactly. Though judging by the address and position of the
dereference a NULL crtc looks most likely.
-Chris

---
drivers/gpu/drm/i915/i915_irq.c | 24 +++++++++++++++++-------
1 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index f0c87bd..d999d00 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -274,24 +274,34 @@ int i915_get_crtc_scanoutpos(struct drm_device *dev, int pipe,
return ret;
}

-int i915_get_vblank_timestamp(struct drm_device *dev, int crtc,
+int i915_get_vblank_timestamp(struct drm_device *dev, int pipe,
int *max_error,
struct timeval *vblank_time,
unsigned flags)
{
- struct drm_crtc *drmcrtc;
+ struct drm_crtc *crtc;

- if (crtc < 0 || crtc >= dev->num_crtcs) {
- DRM_ERROR("Invalid crtc %d\n", crtc);
+ if (pipe < 0 || pipe >= dev->num_crtcs) {
+ DRM_ERROR("Invalid crtc %d\n", pipe);
return -EINVAL;
}

/* Get drm_crtc to timestamp: */
- drmcrtc = intel_get_crtc_for_pipe(dev, crtc);
+ crtc = intel_get_crtc_for_pipe(dev, pipe);
+ if (crtc == NULL) {
+ DRM_ERROR("Invalid crtc %d\n", pipe);
+ return -EINVAL;
+ }
+
+ if (!crtc->enabled) {
+ DRM_DEBUG_KMS("crtc %d is disabled\n", pipe);
+ return -EBUSY;
+ }

/* Helper routine in DRM core does all the work: */
- return drm_calc_vbltimestamp_from_scanoutpos(dev, crtc, max_error,
- vblank_time, flags, drmcrtc);
+ return drm_calc_vbltimestamp_from_scanoutpos(dev, pipe, max_error,
+ vblank_time, flags,
+ crtc);
}

/*
--
1.7.2.3


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