[coreboot-gerrit] Change in coreboot[master]: libpayload: cbgfx: Fix potential overflowing expression

[Patrick Georgi (Code Review)]

Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/38987 )

Change subject: libpayload: cbgfx: Fix potential overflowing expression
......................................................................

libpayload: cbgfx: Fix potential overflowing expression

BRANCH=none
BUG=none
TEST=none

Change-Id: Icd37a6abc01d9fcbcf54525d47b15c9930a9b9fb
Signed-off-by: Yu-Ping Wu 
Found-by: Coverity Scan #1419491
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38987
Tested-by: build bot (Jenkins) 
Reviewed-by: Patrick Georgi 
---
M payloads/libpayload/drivers/video/graphics.c
1 file changed, 3 insertions(+), 3 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Patrick Georgi: Looks good to me, approved

diff --git a/payloads/libpayload/drivers/video/graphics.c b/payloads/libpayload/drivers/video/graphics.c
index 8cb984b8..9494de3 100644
--- a/payloads/libpayload/drivers/video/graphics.c
+++ b/payloads/libpayload/drivers/video/graphics.c
@@ -349,8 +349,8 @@
    /* Use 64 bits to avoid overflow */
    int32_t x, y;
    uint64_t yy;
-	const uint64_t rrx = r.x * r.x, rry = r.y * r.y;
-	const uint64_t ssx = s.x * s.x, ssy = s.y * s.y;
+	const uint64_t rrx = (uint64_t)r.x * r.x, rry = (uint64_t)r.y * r.y;
+	const uint64_t ssx = (uint64_t)s.x * s.x, ssy = (uint64_t)s.y * s.y;
    x_begin = 0;
    x_end = 0;
    for (y = r.y - 1; y >= 0; y--) {
@@ -358,7 +358,7 @@
    	 * The inequality is valid in the beginning of each iteration:
    	 * y^2 + x_end^2 < r^2
    	 */
-		yy = y * y;
+		yy = (uint64_t)y * y;
    	/* Check yy/ssy + xx/ssx < 1 */
    	while (yy * ssx + x_begin * x_begin * ssy < ssx * ssy)
    		x_begin++;