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memory out of bounds read in update_read_bitmap_data #6005

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@hac425xxx

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@hac425xxx

vuln code


static BOOL update_read_bitmap_data(rdpUpdate* update, wStream* s, BITMAP_DATA* bitmapData)
{
	WINPR_UNUSED(update);
	if (Stream_GetRemainingLength(s) < 18)
		return FALSE;

	Stream_Read_UINT16(s, bitmapData->destLeft);
	Stream_Read_UINT16(s, bitmapData->destTop);
	Stream_Read_UINT16(s, bitmapData->destRight);
	Stream_Read_UINT16(s, bitmapData->destBottom);
	Stream_Read_UINT16(s, bitmapData->width);
	Stream_Read_UINT16(s, bitmapData->height);
	Stream_Read_UINT16(s, bitmapData->bitsPerPixel);
	Stream_Read_UINT16(s, bitmapData->flags);
	Stream_Read_UINT16(s, bitmapData->bitmapLength);
        
       // now use 18 byte in s


	if (bitmapData->flags & BITMAP_COMPRESSION)
	{
		if (!(bitmapData->flags & NO_BITMAP_COMPRESSION_HDR))
		{
                        // below read data from stream without check stream's size
			Stream_Read_UINT16(s,
			                   bitmapData->cbCompFirstRowSize); /* cbCompFirstRowSize (2 bytes) */
			Stream_Read_UINT16(s,
			                   bitmapData->cbCompMainBodySize); /* cbCompMainBodySize (2 bytes) */
			Stream_Read_UINT16(s, bitmapData->cbScanWidth);     /* cbScanWidth (2 bytes) */
			Stream_Read_UINT16(s,
			                   bitmapData->cbUncompressedSize); /* cbUncompressedSize (2 bytes) */
			bitmapData->bitmapLength = bitmapData->cbCompMainBodySize;
		}

		bitmapData->compressed = TRUE;
	}
	else
		bitmapData->compressed = FALSE;

	if (Stream_GetRemainingLength(s) < bitmapData->bitmapLength)
		return FALSE;

The function first verifies that the length of s cannot be less than 18, and then reads 18 bytes later.

If bitmapData-> flags & BITMAP_COMPRESSION and ! (BitmapData-> flags & NO_BITMAP_COMPRESSION_HDR) , it will continue to read data from the stream without check if the length in the stream is enough

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