linux-kernel - [PATCH] kernel: drm/vmwgfx: limit the number of mip levels in vmw_gb_surface_define

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Message-Id: <20170330102712.3123-1-vdronov@redhat.com>
Date:   Thu, 30 Mar 2017 12:27:12 +0200
From:   Vladis Dronov <vdronov@...hat.com>
To:     VMware Graphics <linux-graphics-maintainer@...are.com>,
        Sinclair Yeh <syeh@...are.com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     Vladis Dronov <vdronov@...hat.com>
Subject: [PATCH] kernel: drm/vmwgfx: limit the number of mip levels in vmw_gb_surface_define_ioctl()

The 'req->mip_levels' parameter in vmw_gb_surface_define_ioctl() is
a user-controlled 'uint32_t' value which is used as a loop count limit.
This can lead to a kernel lockup and DoS. Add check for 'req->mip_levels'.

References:
https://bugzilla.redhat.com/show_bug.cgi?id=1437431
Signed-off-by: Vladis Dronov <vdronov@...hat.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
index b445ce9..b30824b 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -1281,6 +1281,10 @@ int vmw_gb_surface_define_ioctl(struct drm_device *dev, void *data,
 	if (req->multisample_count != 0)
 		return -EINVAL;
 
+	if (req->mip_levels > DRM_VMW_MAX_SURFACE_FACES *
+	    DRM_VMW_MAX_MIP_LEVELS)
+		return -EINVAL;
+
 	if (unlikely(vmw_user_surface_size == 0))
 		vmw_user_surface_size = ttm_round_pot(sizeof(*user_srf)) +
 			128;
-- 
2.9.3