From 045a044e8ae79db9244593fbce154cdf6e843273 Mon Sep 17 00:00:00 2001 From: newsoft Date: Fri, 15 Aug 2014 16:31:13 +0200 Subject: [PATCH] Fix integer overflow in MallocFrameBuffer() Promote integers to uint64_t to avoid integer overflow issue during frame buffer allocation for very large screen sizes --- libvncclient/vncviewer.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/libvncclient/vncviewer.c b/libvncclient/vncviewer.c index 3b16a6f..24bc6f8 100644 --- a/libvncclient/vncviewer.c +++ b/libvncclient/vncviewer.c @@ -82,9 +82,27 @@ static char* ReadPassword(rfbClient* client) { #endif } static rfbBool MallocFrameBuffer(rfbClient* client) { +uint64_t allocSize; + if(client->frameBuffer) free(client->frameBuffer); - client->frameBuffer=malloc(client->width*client->height*client->format.bitsPerPixel/8); + + /* SECURITY: promote 'width' into uint64_t so that the multiplication does not overflow + 'width' and 'height' are 16-bit integers per RFB protocol design + SIZE_MAX is the maximum value that can fit into size_t + */ + allocSize = (uint64_t)client->width * client->height * client->format.bitsPerPixel/8; + + if (allocSize >= SIZE_MAX) { + rfbClientErr("CRITICAL: cannot allocate frameBuffer, requested size is too large\n"); + return FALSE; + } + + client->frameBuffer=malloc( (size_t)allocSize ); + + if (client->frameBuffer == NULL) + rfbClientErr("CRITICAL: frameBuffer allocation failed, requested size too large or not enough memory?\n"); + return client->frameBuffer?TRUE:FALSE; }