diff --git a/msm8084/libhwcomposer/hwc.cpp b/msm8084/libhwcomposer/hwc.cpp
index d25afbf5..185c1e7d 100644
--- a/msm8084/libhwcomposer/hwc.cpp
+++ b/msm8084/libhwcomposer/hwc.cpp
@@ -196,6 +196,18 @@ static void setNumActiveDisplays(hwc_context_t *ctx, int numDisplays,
     }
 }
 
+static bool validDisplay(int disp) {
+    switch(disp) {
+        case HWC_DISPLAY_PRIMARY:
+        case HWC_DISPLAY_EXTERNAL:
+        case HWC_DISPLAY_VIRTUAL:
+            return true;
+            break;
+        default:
+            return false;
+    }
+}
+
 static void reset(hwc_context_t *ctx, int numDisplays,
                   hwc_display_contents_1_t** displays) {
 
@@ -387,6 +399,10 @@ static int hwc_eventControl(struct hwc_composer_device_1* dev, int dpy,
     ATRACE_CALL();
     int ret = 0;
     hwc_context_t* ctx = (hwc_context_t*)(dev);
+
+    if (!validDisplay(dpy)) {
+        return -EINVAL;
+    }
     switch(event) {
         case HWC_EVENT_VSYNC:
             if (ctx->vstate.enable == enable)
@@ -419,6 +435,10 @@ static int hwc_setPowerMode(struct hwc_composer_device_1* dev, int dpy,
     hwc_context_t* ctx = (hwc_context_t*)(dev);
     int ret = 0, value = 0;
 
+    if (!validDisplay(dpy)) {
+        return -EINVAL;
+    }
+
     Locker::Autolock _l(ctx->mDrawLock);
     ALOGD_IF(POWER_MODE_DEBUG, "%s: Setting mode %d on display: %d",
             __FUNCTION__, mode, dpy);
@@ -734,6 +754,10 @@ int hwc_getDisplayConfigs(struct hwc_composer_device_1* dev, int disp,
         uint32_t* configs, size_t* numConfigs) {
     int ret = 0;
     hwc_context_t* ctx = (hwc_context_t*)(dev);
+
+    if (!validDisplay(disp)) {
+        return -EINVAL;
+    }
     disp = getDpyforExternalDisplay(ctx, disp);
     //Currently we allow only 1 config, reported as config id # 0
     //This config is passed in to getDisplayAttributes. Ignored for now.
@@ -764,6 +788,10 @@ int hwc_getDisplayAttributes(struct hwc_composer_device_1* dev, int disp,
         uint32_t /*config*/, const uint32_t* attributes, int32_t* values) {
 
     hwc_context_t* ctx = (hwc_context_t*)(dev);
+
+    if (!validDisplay(disp)) {
+        return -EINVAL;
+    }
     disp = getDpyforExternalDisplay(ctx, disp);
     //If hotpluggable displays(i.e, HDMI, WFD) are inactive return error
     if( (disp != HWC_DISPLAY_PRIMARY) && !ctx->dpyAttr[disp].connected) {
diff --git a/msm8226/libhwcomposer/hwc.cpp b/msm8226/libhwcomposer/hwc.cpp
index 32f33afa..0ff970a9 100644
--- a/msm8226/libhwcomposer/hwc.cpp
+++ b/msm8226/libhwcomposer/hwc.cpp
@@ -206,6 +206,18 @@ static void setNumActiveDisplays(hwc_context_t *ctx, int numDisplays,
     }
 }
 
+static bool validDisplay(int disp) {
+    switch(disp) {
+        case HWC_DISPLAY_PRIMARY:
+        case HWC_DISPLAY_EXTERNAL:
+        case HWC_DISPLAY_VIRTUAL:
+            return true;
+            break;
+        default:
+            return false;
+    }
+}
+
 static void reset(hwc_context_t *ctx, int numDisplays,
                   hwc_display_contents_1_t** displays) {
 
@@ -387,6 +399,10 @@ static int hwc_eventControl(struct hwc_composer_device_1* dev, int dpy,
     ATRACE_CALL();
     int ret = 0;
     hwc_context_t* ctx = (hwc_context_t*)(dev);
+
+    if (!validDisplay(dpy)) {
+        return -EINVAL;
+    }
     switch(event) {
         case HWC_EVENT_VSYNC:
             if (ctx->vstate.enable == enable)
@@ -419,6 +435,10 @@ static int hwc_setPowerMode(struct hwc_composer_device_1* dev, int dpy,
     hwc_context_t* ctx = (hwc_context_t*)(dev);
     int ret = 0, value = 0;
 
+    if (!validDisplay(dpy)) {
+        return -EINVAL;
+    }
+
     Locker::Autolock _l(ctx->mDrawLock);
     ALOGV_IF(POWER_MODE_DEBUG, "%s: Setting mode %d on display: %d",
             __FUNCTION__, mode, dpy);
@@ -764,6 +784,10 @@ int hwc_getDisplayConfigs(struct hwc_composer_device_1* dev, int disp,
         uint32_t* configs, size_t* numConfigs) {
     int ret = 0;
     hwc_context_t* ctx = (hwc_context_t*)(dev);
+
+    if (!validDisplay(dpy)) {
+        return -EINVAL;
+    }
     disp = getDpyforExternalDisplay(ctx, disp);
     //Currently we allow only 1 config, reported as config id # 0
     //This config is passed in to getDisplayAttributes. Ignored for now.
@@ -794,6 +818,10 @@ int hwc_getDisplayAttributes(struct hwc_composer_device_1* dev, int disp,
         uint32_t /*config*/, const uint32_t* attributes, int32_t* values) {
 
     hwc_context_t* ctx = (hwc_context_t*)(dev);
+
+    if (!validDisplay(dpy)) {
+        return -EINVAL;
+    }
     disp = getDpyforExternalDisplay(ctx, disp);
     //If hotpluggable displays(i.e, HDMI, WFD) are inactive return error
     if( (disp != HWC_DISPLAY_PRIMARY) && !ctx->dpyAttr[disp].connected) {
diff --git a/msm8960/libhwcomposer/hwc.cpp b/msm8960/libhwcomposer/hwc.cpp
index f8561735..3d6fb845 100644
--- a/msm8960/libhwcomposer/hwc.cpp
+++ b/msm8960/libhwcomposer/hwc.cpp
@@ -82,6 +82,18 @@ static void hwc_registerProcs(struct hwc_composer_device_1* dev,
     init_vsync_thread(ctx);
 }
 
+static bool validDisplay(int disp) {
+    switch(disp) {
+        case HWC_DISPLAY_PRIMARY:
+        case HWC_DISPLAY_EXTERNAL:
+        case HWC_DISPLAY_VIRTUAL:
+            return true;
+            break;
+        default:
+            return false;
+    }
+}
+
 //Helper
 static void reset(hwc_context_t *ctx, int numDisplays,
                   hwc_display_contents_1_t** displays) {
@@ -244,6 +256,10 @@ static int hwc_eventControl(struct hwc_composer_device_1* dev, int dpy,
 {
     int ret = 0;
     hwc_context_t* ctx = (hwc_context_t*)(dev);
+
+    if (!validDisplay(dpy)) {
+        return -EINVAL;
+    }
     if(!ctx->dpyAttr[dpy].isActive) {
         ALOGE("Display is blanked - Cannot %s vsync",
               enable ? "enable" : "disable");
@@ -271,6 +287,10 @@ static int hwc_blank(struct hwc_composer_device_1* dev, int dpy, int blank)
     ATRACE_CALL();
     hwc_context_t* ctx = (hwc_context_t*)(dev);
 
+    if (!validDisplay(dpy)) {
+        return -EINVAL;
+    }
+
     Locker::Autolock _l(ctx->mBlankLock);
     int ret = 0;
     ALOGD_IF(BLANK_DEBUG, "%s: %s display: %d", __FUNCTION__,
@@ -490,6 +510,11 @@ int hwc_getDisplayConfigs(struct hwc_composer_device_1* dev, int disp,
         uint32_t* configs, size_t* numConfigs) {
     int ret = 0;
     hwc_context_t* ctx = (hwc_context_t*)(dev);
+
+    if (!validDisplay(disp)) {
+        return -EINVAL;
+    }
+
     //in 1.1 there is no way to choose a config, report as config id # 0
     //This config is passed to getDisplayAttributes. Ignore for now.
     switch(disp) {
@@ -518,6 +543,11 @@ int hwc_getDisplayAttributes(struct hwc_composer_device_1* dev, int disp,
         uint32_t config, const uint32_t* attributes, int32_t* values) {
 
     hwc_context_t* ctx = (hwc_context_t*)(dev);
+
+    if (!validDisplay(disp)) {
+        return -EINVAL;
+    }
+
     //If hotpluggable displays are inactive return error
     if(disp == HWC_DISPLAY_EXTERNAL && !ctx->dpyAttr[disp].connected) {
         return -1;
diff --git a/msm8994/libhwcomposer/hwc.cpp b/msm8994/libhwcomposer/hwc.cpp
index a8a248de..d086ef5a 100644
--- a/msm8994/libhwcomposer/hwc.cpp
+++ b/msm8994/libhwcomposer/hwc.cpp
@@ -194,6 +194,18 @@ static bool isHotPluggable(hwc_context_t *ctx, int dpy) {
              ctx->mHDMIDisplay->isHDMIPrimaryDisplay()));
 }
 
+static bool validDisplay(int disp) {
+    switch(disp) {
+        case HWC_DISPLAY_PRIMARY:
+        case HWC_DISPLAY_EXTERNAL:
+        case HWC_DISPLAY_VIRTUAL:
+            return true;
+            break;
+        default:
+            return false;
+    }
+}
+
 static void reset(hwc_context_t *ctx, int numDisplays,
                   hwc_display_contents_1_t** displays) {
 
@@ -425,6 +437,10 @@ static int hwc_eventControl(struct hwc_composer_device_1* dev, int dpy,
     ATRACE_CALL();
     int ret = 0;
     hwc_context_t* ctx = (hwc_context_t*)(dev);
+
+    if (!validDisplay(dpy)) {
+        return -EINVAL;
+    }
     switch(event) {
         case HWC_EVENT_VSYNC:
             if (ctx->vstate.enable == enable)
@@ -457,6 +473,10 @@ static int hwc_setPowerMode(struct hwc_composer_device_1* dev, int dpy,
     hwc_context_t* ctx = (hwc_context_t*)(dev);
     int ret = 0, value = 0;
 
+    if (!validDisplay(dpy)) {
+        return -EINVAL;
+    }
+
     Locker::Autolock _l(ctx->mDrawLock);
     ALOGD_IF(POWER_MODE_DEBUG, "%s: Setting mode %d on display: %d",
             __FUNCTION__, mode, dpy);
@@ -784,6 +804,9 @@ int hwc_getDisplayConfigs(struct hwc_composer_device_1* dev, int disp,
         uint32_t* configs, size_t* numConfigs) {
     hwc_context_t* ctx = (hwc_context_t*)(dev);
 
+    if (!validDisplay(disp)) {
+        return -EINVAL;
+    }
     Locker::Autolock _l(ctx->mDrawLock);
     bool hotPluggable = isHotPluggable(ctx, disp);
     bool isVirtualDisplay = (disp == HWC_DISPLAY_VIRTUAL);
@@ -830,6 +853,9 @@ int hwc_getDisplayAttributes(struct hwc_composer_device_1* dev, int disp,
 
     hwc_context_t* ctx = (hwc_context_t*)(dev);
 
+    if (!validDisplay(disp)) {
+        return -EINVAL;
+    }
     Locker::Autolock _l(ctx->mDrawLock);
     bool hotPluggable = isHotPluggable(ctx, disp);
     bool isVirtualDisplay = (disp == HWC_DISPLAY_VIRTUAL);
@@ -923,6 +949,9 @@ int hwc_getActiveConfig(struct hwc_composer_device_1* dev, int disp)
 {
     hwc_context_t* ctx = (hwc_context_t*)(dev);
 
+    if (!validDisplay(disp)) {
+        return -EINVAL;
+    }
     Locker::Autolock _l(ctx->mDrawLock);
     bool hotPluggable = isHotPluggable(ctx, disp);
     bool isVirtualDisplay = (disp == HWC_DISPLAY_VIRTUAL);
@@ -947,6 +976,9 @@ int hwc_setActiveConfig(struct hwc_composer_device_1* dev, int disp, int index)
 {
     hwc_context_t* ctx = (hwc_context_t*)(dev);
 
+    if (!validDisplay(disp)) {
+        return -EINVAL;
+    }
     Locker::Autolock _l(ctx->mDrawLock);
     bool hotPluggable = isHotPluggable(ctx, disp);
     bool isVirtualDisplay = (disp == HWC_DISPLAY_VIRTUAL);