drm/i915/dsi: defend gpio table against out of bounds access

commit 4db3a2448ec8902310acb78de39b6227a9a56ac8 upstream.

Do not blindly trust the VBT data used for indexing.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/cc32d40c2b47f2d2151811855ac2c3dabab1d57d.1454582914.git.jani.nikula@intel.com
(cherry picked from commit 5d2d0a12d3d08bf50434f0b5947bb73bac04b941)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c b/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
index 21a0d348cedc2a716e79105557215a1736d2ac76..9db5dc8f4521977987d46c97bbed2d779f4d3a98 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
+++ b/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
@@ -173,6 +173,11 @@ static u8 *mipi_exec_gpio(struct intel_dsi *intel_dsi, u8 *data)
        /* pull up/down */
        action = *data++;
 
+       if (gpio >= ARRAY_SIZE(gtable)) {
+               DRM_DEBUG_KMS("unknown gpio %u\n", gpio);
+               goto out;
+       }
+
        function = gtable[gpio].function_reg;
        pad = gtable[gpio].pad_reg;
 
@@ -190,6 +195,7 @@ static u8 *mipi_exec_gpio(struct intel_dsi *intel_dsi, u8 *data)
        vlv_gpio_nc_write(dev_priv, pad, val);
        mutex_unlock(&dev_priv->dpio_lock);
 
+out:
        return data;
 }