cxl: Fix error path on bad ioctl

commit cec422c11caeeccae709e9942058b6b644ce434c upstream.

Fix error path if we can't copy user structure on CXL_IOCTL_START_WORK
ioctl. We shouldn't unlock the context status mutex as it was not
locked (yet).

Fixes: 0712dc7e73e5 ("cxl: Fix issues when unmapping contexts")
Signed-off-by: Frederic Barrat <[email protected]>
Reviewed-by: Vaibhav Jain <[email protected]>
Reviewed-by: Andrew Donnellan <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Lee Jones <[email protected]>
Change-Id: I89526602b62553fa6963435261ef93467d03bb3a

Author: Frederic Barrat

drivers/misc/cxl/file.c

@@ -142,11 +142,8 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
 
 	/* Do this outside the status_mutex to avoid a circular dependency with
 	 * the locking in cxl_mmap_fault() */
-	if (copy_from_user(&work, uwork,
-			   sizeof(struct cxl_ioctl_start_work))) {
-		rc = -EFAULT;
-		goto out;
-	}
+	if (copy_from_user(&work, uwork, sizeof(work)))
+		return -EFAULT;
 
 	mutex_lock(&ctx->status_mutex);
 	if (ctx->status != OPENED) {