fix possible segfault and negative height

src/driver/colorgradient.cpp

@@ -62,6 +62,9 @@ uint8_t CColorGradient::limitChar(int c)
 
 fb_pixel_t* CColorGradient::gradientColorToTransparent(fb_pixel_t col, fb_pixel_t *gradientBuf, int bSize, int /*mode*/, int /*intensity*/)
 {
+	if (bSize < 1)
+		return gradientBuf;
+
 	if (gradientBuf == NULL) {
 		gradientBuf = (fb_pixel_t*) malloc(bSize * sizeof(fb_pixel_t));
 		if (gradientBuf == NULL) {
@@ -94,6 +97,8 @@ fb_pixel_t* CColorGradient::gradientColorToTransparent(fb_pixel_t col, fb_pixel_
 
 fb_pixel_t* CColorGradient::gradientOneColor(fb_pixel_t col, fb_pixel_t *gradientBuf, int bSize, int mode, int intensity, uint8_t v_min, uint8_t v_max, uint8_t s)
 {
+	if (bSize < 1)
+		return gradientBuf;
 
 	if (gradientBuf == NULL) {
 		gradientBuf = (fb_pixel_t*) malloc(bSize * sizeof(fb_pixel_t));

src/driver/framebuffer.cpp

@@ -676,7 +676,7 @@ fb_pixel_t* CFrameBuffer::paintBoxRel2Buf(const int dx, const int dy, const int
 {
 	if (!getActive())
 		return buf;
-	if (dx == 0 || dy == 0) {
+	if (dx < 1 || dy < 1) {
 		dprintf(DEBUG_INFO, "[CFrameBuffer] [%s - %d]: radius %d, dx %d dy %d\n", __func__, __LINE__, radius, dx, dy);
 		return buf;
 	}
@@ -2026,6 +2026,9 @@ void CFrameBuffer::blit2FB(void *fbbuff, uint32_t width, uint32_t height, uint32
 
 void CFrameBuffer::blitBox2FB(const fb_pixel_t* boxBuf, uint32_t width, uint32_t height, uint32_t xoff, uint32_t yoff)
 {
+	if(width <1 || height <1 || !boxBuf )
+		return;
+
 	uint32_t xc = (width > xRes) ? (uint32_t)xRes : width;
 	uint32_t yc = (height > yRes) ? (uint32_t)yRes : height;
 

src/gui/components/cc_frm_scrollbar.cpp

@@ -136,6 +136,8 @@ void CComponentsScrollBar::initSegments()
 
 	//calculate height of segment container
 	int h_seg_obj = height - 2*sb_up_obj->getHeight() - 3*append_y_offset;
+	if(h_seg_obj < 0)
+		h_seg_obj = 0;
 
 	//init segment container
 	if (sb_segments_obj == NULL){
@@ -154,6 +156,8 @@ void CComponentsScrollBar::initSegments()
 	//set y position of 1st segment and set height of segments
 	int y_seg = 1+ append_y_offset;
 	int h_seg = sb_segments_obj->getHeight()/sb_segments_count - append_y_offset;
+	if(h_seg < 0)
+		h_seg = 0;
 
 	//create and add segments to segment container
 	for(u_int8_t i=0; i<sb_segments_count; i++){

src/gui/infoviewer.cpp

@@ -445,6 +445,9 @@ void CInfoViewer::paintHead()
 void CInfoViewer::paintBody()
 {
 	int h_body = InfoHeightY - header_height - OFFSET_SHADOW;
+	if(h_body < 0)
+		h_body = 0;
+
 	infoViewerBB->initBBOffset();
 	if (!zap_mode)
 		h_body += infoViewerBB->bottom_bar_offset;