[PATCH] kernel: drm/vmwgfx: limit the number of mip levels in vmw_gb_surface_define_ioctl()

From: Vladis Dronov
Date: Thu Mar 30 2017 - 06:27:35 EST


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@xxxxxxxxxx>
---
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