[PATCH v4] wintab32: Use 64-bit math in ScaleForContext.
John Chadwick
john at jchw.io
Sun Nov 17 16:26:40 CST 2019
With some tablet configurations, the InExt value passed to
ScaleForContext can be very large, leading to an integer overflow. Using
MulDiv prevents this problem by internally using 64-bit math.
Signed-off-by: John Chadwick <john at jchw.io>
---
dlls/wintab32/context.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/dlls/wintab32/context.c b/dlls/wintab32/context.c
index 0514dd78b4..ff9a4ca677 100644
--- a/dlls/wintab32/context.c
+++ b/dlls/wintab32/context.c
@@ -178,9 +178,9 @@ int TABLET_PostTabletMessage(LPOPENCONTEXT newcontext, UINT msg, WPARAM wParam,
static inline DWORD ScaleForContext(DWORD In, LONG InOrg, LONG InExt, LONG OutOrg, LONG OutExt)
{
if (((InExt > 0 )&&(OutExt > 0)) || ((InExt<0) && (OutExt < 0)))
- return ((In - InOrg) * abs(OutExt) / abs(InExt)) + OutOrg;
+ return MulDiv(In - InOrg, abs(OutExt), abs(InExt)) + OutOrg;
else
- return ((abs(InExt) - (In - InOrg))*abs(OutExt) / abs(InExt)) + OutOrg;
+ return MulDiv(abs(InExt) - (In - InOrg), abs(OutExt), abs(InExt)) + OutOrg;
}
LPOPENCONTEXT AddPacketToContextQueue(LPWTPACKET packet, HWND hwnd)
--
2.23.0
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