[Intel-gfx] [PATCH] drm/i915: Fix crash when failing to parse MIPI VBT

[Daniel Vetter]

On Thu, Jul 24, 2014 at 03:16:12PM +0100, rafael.barbalho at intel.com wrote:
> From: Rafael Barbalho <rafael.barbalho at intel.com>
> 
> This particular nasty presented itself while trying to register the
> intelfb device (intel_fbdev.c). During the process of registering the device
> the driver will disable the crtc via i9xx_crtc_disable. These will
> also disable the panel using the generic mipi panel functions in
> dsi_mod_vbt_generic.c. The stale MIPI generic data sequence pointers would
> cause a crash within those functions. However, all of this is happening
> while console_lock is held from do_register_framebuffer inside fbcon.c. Which
> means that you got kernel log and just the device appearing to reboot/hang for
> no apparent reason.

CONFIG_I915_FBDEV=n for when the console_lock gets in the way.

> The fault started from the FB_EVENT_FB_REGISTERED event using the
> fb_notifier_call_chain call in fbcon.c.
> 
> Cc: Shobhit Kumar <shobhit.kumar at intel.com>
> Signed-off-by: Rafael Barbalho <rafael.barbalho at intel.com>

Queued for -next, thanks for the patch.
-Daniel
> ---
>  drivers/gpu/drm/i915/intel_bios.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index 608ed30..a669550 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -878,7 +878,7 @@ err:
>  
>  	/* error during parsing so set all pointers to null
>  	 * because of partial parsing */
> -	memset(dev_priv->vbt.dsi.sequence, 0, MIPI_SEQ_MAX);
> +	memset(dev_priv->vbt.dsi.sequence, 0, sizeof(dev_priv->vbt.dsi.sequence));
>  }
>  
>  static void parse_ddi_port(struct drm_i915_private *dev_priv, enum port port,
> -- 
> 2.0.2
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch