[PATCH] drm/bochs: avoided potential integer overflow

From: Maxim Korotkov
Date: Wed Mar 13 2024 - 07:26:43 EST


if the bochs_dispi_read() function returns a value between
0x8000 and 0xFFFF, then an overflow may occurs.

Found by Security Code and Linux Verification Center (linuxtesting.org)

Signed-off-by: Maxim Korotkov <m.korotkov@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/tiny/bochs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
index c23c9f0cf49c..ad31049f9779 100644
--- a/drivers/gpu/drm/tiny/bochs.c
+++ b/drivers/gpu/drm/tiny/bochs.c
@@ -240,7 +240,7 @@ static int bochs_hw_init(struct drm_device *dev)

id = bochs_dispi_read(bochs, VBE_DISPI_INDEX_ID);
mem = bochs_dispi_read(bochs, VBE_DISPI_INDEX_VIDEO_MEMORY_64K)
- * 64 * 1024;
+ * mul_u32_u32(64, 1024);
if ((id & 0xfff0) != VBE_DISPI_ID0) {
DRM_ERROR("ID mismatch\n");
return -ENODEV;
--
2.34.1