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 <robdclark@gmail.com>

drivers/gpu/drm/msm/msm_gem_submit.c

@@ -23,7 +23,6 @@
  * 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
@@ -77,7 +76,7 @@ static int submit_lookup_objects(struct msm_gem_submit *submit,
 			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;
@@ -369,6 +368,18 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 			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;
+		}
+
 		ret = submit_bo(submit, submit_cmd.submit_idx,
 				&msm_obj, &iova, NULL);
 		if (ret)