drm/msm: validate flags, etc

After reading a nice article on LWN[1], I went back and double checked
my handling of invalid-input checking. Turns out there were a couple
places I had missed.

Since the driver is fairly young, and the devices it supports are really
only just barely usable for basic stuff (serial console) with an
upstream kernel, I think we should fix this now and revert specific
parts of this patch later in the unlikely event that a regression is
reported.

[1] https://lwn.net/Articles/588444/

Signed-off-by: Rob Clark <[e-mail]>

drivers/gpu/drm/msm/msm_drv.c

···
 		struct drm_file *file)
 {
 	struct drm_msm_gem_new *args = data;
+
+	if (args->flags & ~MSM_BO_FLAGS) {
+		DRM_ERROR("invalid flags: %08x\n", args->flags);
+		return -EINVAL;
+	}
+
 	return msm_gem_new_handle(dev, file, args->size,
 			args->flags, &args->handle);
 }
···
 	struct drm_msm_gem_cpu_prep *args = data;
 	struct drm_gem_object *obj;
 	int ret;
+
+	if (args->op & ~MSM_PREP_FLAGS) {
+		DRM_ERROR("invalid op: %08x\n", args->op);
+		return -EINVAL;
+	}
 
 	obj = drm_gem_object_lookup(dev, file, args->handle);
 	if (!obj)
···
 		struct drm_file *file)
 {
 	struct drm_msm_wait_fence *args = data;
-	return msm_wait_fence_interruptable(dev, args->fence, &TS(args->timeout));
+
+	if (args->pad) {
+		DRM_ERROR("invalid pad: %08x\n", args->pad);
+		return -EINVAL;
+	}
+
+	return msm_wait_fence_interruptable(dev, args->fence,
+			&TS(args->timeout));
 }
 
 static const struct drm_ioctl_desc msm_ioctls[] = {

drivers/gpu/drm/msm/msm_gem_submit.c

···
  * Cmdstream submission:
  */
 
-#define BO_INVALID_FLAGS ~(MSM_SUBMIT_BO_READ | MSM_SUBMIT_BO_WRITE)
 /* make sure these don't conflict w/ MSM_SUBMIT_BO_x */
 #define BO_VALID    0x8000
 #define BO_LOCKED   0x4000
···
 			goto out_unlock;
 		}
 
-		if (submit_bo.flags & BO_INVALID_FLAGS) {
+		if (submit_bo.flags & ~MSM_SUBMIT_BO_FLAGS) {
 			DRM_ERROR("invalid flags: %x\n", submit_bo.flags);
 			ret = -EINVAL;
 			goto out_unlock;
···
 		ret = copy_from_user(&submit_cmd, userptr, sizeof(submit_cmd));
 		if (ret) {
 			ret = -EFAULT;
+			goto out;
+		}
+
+		/* validate input from userspace: */
+		switch (submit_cmd.type) {
+		case MSM_SUBMIT_CMD_BUF:
+		case MSM_SUBMIT_CMD_IB_TARGET_BUF:
+		case MSM_SUBMIT_CMD_CTX_RESTORE_BUF:
+			break;
+		default:
+			DRM_ERROR("invalid type: %08x\n", submit_cmd.type);
+			ret = -EINVAL;
 			goto out;
 		}
 

include/uapi/drm/msm_drm.h

···
 #define MSM_BO_WC            0x00020000
 #define MSM_BO_UNCACHED      0x00040000
 
+#define MSM_BO_FLAGS         (MSM_BO_SCANOUT | \
+                              MSM_BO_GPU_READONLY | \
+                              MSM_BO_CACHED | \
+                              MSM_BO_WC | \
+                              MSM_BO_UNCACHED)
+
 struct drm_msm_gem_new {
 	uint64_t size;           /* in */
 	uint32_t flags;          /* in, mask of MSM_BO_x */
···
 #define MSM_PREP_READ        0x01
 #define MSM_PREP_WRITE       0x02
 #define MSM_PREP_NOSYNC      0x04
+
+#define MSM_PREP_FLAGS       (MSM_PREP_READ | MSM_PREP_WRITE | MSM_PREP_NOSYNC)
 
 struct drm_msm_gem_cpu_prep {
 	uint32_t handle;         /* in */
···
  */
 #define MSM_SUBMIT_BO_READ             0x0001
 #define MSM_SUBMIT_BO_WRITE            0x0002
+
+#define MSM_SUBMIT_BO_FLAGS            (MSM_SUBMIT_BO_READ | MSM_SUBMIT_BO_WRITE)
+
 struct drm_msm_gem_submit_bo {
 	uint32_t flags;          /* in, mask of MSM_SUBMIT_BO_x */
 	uint32_t handle;         /* in, GEM handle */