[lvc-project] Fwd: [PATCH] drm/bochs: avoided potential integer overflow

[Maxim Korotkov]

-------- Forwarded Message --------
Subject: [PATCH] drm/bochs: avoided potential integer overflow
Date: Wed, 13 Mar 2024 14:25:18 +0300
From: Maxim Korotkov <korotkov.maxim.s at gmail.com>
To: Gerd Hoffmann <kraxel at redhat.com>
CC: Maxim Korotkov <korotkov.maxim.s at gmail.com>, Maarten Lankhorst 
<maarten.lankhorst at linux.intel.com>, Maxime Ripard <mripard at kernel.org>, 
Thomas Zimmermann <tzimmermann at suse.de>, David Airlie 
<airlied at gmail.com>, Daniel Vetter <daniel at ffwll.ch>, 
virtualization at lists.linux.dev, dri-devel at lists.freedesktop.org, 
linux-kernel at vger.kernel.org, Maxim Korotkov <m.korotkov at securitycode.ru>

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 at securitycode.ru>
---
  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