linux-kernel - [PATCH] drm: prevent a harmless integer overflow in drm_legacy_sg

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Message-ID: <20200228092321.axulddmkxrujkmas@kili.mountain>
Date:   Fri, 28 Feb 2020 12:23:21 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Cc:     Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: [PATCH] drm: prevent a harmless integer overflow in
 drm_legacy_sg_alloc()

There is an integer overflow when we round up to PAGE_SIZE, but it's
harmless because we never re-use "request->size" for anything meaningful.

Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
This code predates git.

 drivers/gpu/drm/drm_scatter.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_scatter.c b/drivers/gpu/drm/drm_scatter.c
index d5c386154246..ca520028b2cb 100644
--- a/drivers/gpu/drm/drm_scatter.c
+++ b/drivers/gpu/drm/drm_scatter.c
@@ -99,6 +99,9 @@ int drm_legacy_sg_alloc(struct drm_device *dev, void *data,
 	if (!drm_core_check_feature(dev, DRIVER_SG))
 		return -EOPNOTSUPP;
 
+	if (request->size > SIZE_MAX - PAGE_SIZE)
+		return -EINVAL;
+
 	if (dev->sg)
 		return -EINVAL;
 
-- 
2.11.0