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commit 045a044e8ae79db9244593fbce154cdf6e843273
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Author: newsoft <newsoft@MacBook-Air-de-newsoft-2.local>
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Date: Fri Aug 15 16:31:13 2014 +0200
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Fix integer overflow in MallocFrameBuffer()
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Promote integers to uint64_t to avoid integer overflow issue during
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frame buffer allocation for very large screen sizes
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diff --git a/libvncclient/vncviewer.c b/libvncclient/vncviewer.c
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index 3b16a6f..24bc6f8 100644
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--- a/libvncclient/vncviewer.c
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+++ b/libvncclient/vncviewer.c
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@@ -82,9 +82,27 @@ static char* ReadPassword(rfbClient* client) {
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#endif
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}
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static rfbBool MallocFrameBuffer(rfbClient* client) {
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+uint64_t allocSize;
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+
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if(client->frameBuffer)
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free(client->frameBuffer);
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- client->frameBuffer=malloc(client->width*client->height*client->format.bitsPerPixel/8);
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+
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+ /* SECURITY: promote 'width' into uint64_t so that the multiplication does not overflow
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+ 'width' and 'height' are 16-bit integers per RFB protocol design
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+ SIZE_MAX is the maximum value that can fit into size_t
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+ */
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+ allocSize = (uint64_t)client->width * client->height * client->format.bitsPerPixel/8;
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+
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+ if (allocSize >= SIZE_MAX) {
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+ rfbClientErr("CRITICAL: cannot allocate frameBuffer, requested size is too large\n");
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+ return FALSE;
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+ }
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+
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+ client->frameBuffer=malloc( (size_t)allocSize );
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+
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+ if (client->frameBuffer == NULL)
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+ rfbClientErr("CRITICAL: frameBuffer allocation failed, requested size too large or not enough memory?\n");
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+
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return client->frameBuffer?TRUE:FALSE;
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}
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