intel_th: msu: Fix overflow in shift of an unsigned int

The shift of the unsigned int win->nr_blocks by PAGE_SHIFT may
potentially overflow. Note that the intended return of this shift
is expected to be a size_t however the shift is being performed as
an unsigned int.  Fix this by casting win->nr_blocks to a size_t
before performing the shift.

Addresses-Coverity: ("Unintentional integer overflow")
Fixes: 615c164d ("intel_th: msu: Introduce buffer interface")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/lkml/20190726113151.8967-1-colin.king@canonical.com/
Link: https://lore.kernel.org/r/20191028070651.9770-5-alexander.shishkin@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/intel_th/msu.c

@@ -327,7 +327,7 @@ static size_t msc_win_total_sz(struct msc_window *win)
 		struct msc_block_desc *bdesc = sg_virt(sg);
 
 		if (msc_block_wrapped(bdesc))
-			return win->nr_blocks << PAGE_SHIFT;
+			return (size_t)win->nr_blocks << PAGE_SHIFT;
 
 		size += msc_total_sz(bdesc);
 		if (msc_block_last_written(bdesc))